Monthly seasonality of FTSE 100 Index

Does the FTSE 100 Index display a monthly seasonality?

[We last looked at this in 2014, so time to see if anything has changed.]

Positive returns

The following chart shows the proportion of months that have seen positive returns for the FTSE 100 Index since 1980. For example, the index rose in April in 28 years since since 1980 (76%).

FTSE 100 Index positive returns by month [1980-2016]

Broadly, the pattern of behaviour has not changed greatly in the last two and a half years. The months which have seen the highest number of positive returns are still April, October and December.

But in recent years, since 2000, February has been getting relatively stronger, while January and March relatively weaker. Since 1980, the proportion of positive return months for January is 59%. but measured from 2000 the figure falls to 35%.

Average returns

The following chart plots the average month returns for the FTSE 100 Index for the period 1980-2016. For example, since 1980 average return in January of the index has been 0.9%

FTSE 100 Index average returns by month [1980-2016]

Similar to the previous study, the standout two strong months of the year since 1980 have been April and December. Although since 2000 the performance of December has been dropping off and has been over-taken by October as the second best performing month in recent years.

The months with the lowest (in fact, negative) returns are still May, June and September. Again, things have changed slightly in recent years, with January equal with September as having the worst average returns since 2000.

The following chart is similar to the above (in that it plots the index average returns by month, the short brown horizontal bars), but it adds a measure of the extent of variation away from the average for each month (the measure is 1 standard deviation).

FTSE 100 Index average returns by month (1SD) [1997]

An obvious observation to make is that the variability of returns around the average are very large for all months. The months that have seen the greatest variability (i.e. volatility) have been September and October, and to a slightly lesser extent January. The months with the lowest variabilility have been April and December.

Cumulative returns

The following chart shows the cumulative returns indexed to 100 for each month. For example, £100 invested in the FTSE 100 only in the month of April from 1980 would have grow to £217 by 2016.

This is not meant to represent real-life investable portfolios (e.g. transaction costs are not included), but to illustrate the large effect the returns differences can have on cumulative performance over a long term,

FTSE 100 Index cumulative returns by month [1980-2016]


  1. The superior returns for April and December can be clearly seen on this chart. Indeed, the close correlation of returns for the two months is remarkable, and rather odd. However, as can be seen, due to the recent couple of weak years for December, performance has been diverging between the the two months.
  2. The most striking change in behaviour is undoubtedly that for January. This was the strongest month for the FTSE 100 Index until the beginning of the millennium, since when its performance has fallen off quite dramatically.
  3. In a less dramatic fashion (than January) the returns for November have decreased strongly since 2005.
  4. The months represented by dashed lines are the six months May to October. These lines can be seen to largely occupy the lower part of chart – which supports the Sell in May effect.
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Monthly seasonality of oil

Does the price of oil display a seasonality pattern?

[We last looked at this in 2014 in this article; time to update the figures.]

To briefly recap, the original study found that since 1986 the price of oil displayed a seasonality for two parts of the year-

  • March-September when WTI is strong, and
  • October- February when the WTI price has been relatively weak

Let’s see if this is still the case.

Mean returns

The following chart plots the average month returns of the price of WTI (West Texas Intermediate) for the period 2000-2016.

Crude Oil (WTI) [2000-2014] Monthly return average

A two-part pattern for the year is still observable, but the periods have shifted slightly.

As can be seen, since 2000, WTI month returns have tended to be high in the period February to June. The strongest month of the year in this period has been February with an average return in the month of 4.8%.

The weak part of the year has also shifted: to September to January. The weakest month has been November, with an average price return of 3.2%.

Positive returns

The following chart plots the  proportion of monthly returns that were positive over the same period.

Crude Oil (WTI) [2000-2014] Monthly return positive

This pattern of positive returns largely supports the preceding analysis.

Since 2002 WTI has seen negative returns in February in only 3 years.

By contrast, September has seen positive returns in only 6 years since 2000.

The new seasonality pattern can thus be summarised as-

  1. February-June when WTI is strong, and
  2. September-January when the WTI price has been relatively weak

Cumulative performance

The following chart plots the cumulative performance of WTI for two portfolios:

  1. WTI (Strong Months) – this holds WTI in just the strong months identified above (February-June), and is in cash for the rest of the year
  2. WTI (Weak Months) – this holds WTI in just the weak months (September-January), and is in cash for the rest of the year

For benchmarking purposes WTI (continuous holding) and the S&P 500 Index are also plotted. All series are re-based to start at 100.

WTI Seasonality Performance [2000-2016]

Starting at 100 in 2000, the WTI (Weak Months) portfolio would have fallen to a value of 16 by 2016. The S&P 500 would have a value of 145, and a continuous holding in WTI a value of 182. But the WTI (Strong Months) portfolio would today have a value of 1047.

Further articles on oil.

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Tuesday reverses Monday

Do market returns on Tuesdays reverse those on Monday?

We first looked at this in 2013 (in this article), so time to see if anything has changed.

First, the following updates the chart to 2016 plotting Tuesday returns for the FTSE 100 Index split by whether the previous day’s returns were positive or negative. Two time periods are considered: 1984-2016 and 2000-2016.

For example, for the longer period, the average return on Tuesday when Monday was up is 0.02%, while the average Tuesday return when Monday was down is 0.09%.

FTSE 100 returns on Tuesdays when Monday was up-down

While the figures have marginally changed from the previous study in 2013, the overall finding is the same: namely that the theory that Tuesday reverses Monday does not seem to hold. Since 1984 it has done so when Monday returns have been negative, but not when they have been positive. 

As in the 2013 study, the theory has been valid for the market since 2000.

The previous study suggested that further analysis might include a filter on the size of the Monday returns. This is done in the following chart, where Tuesday returns are only considered if Monday’s returns were beyond a certain threshold (i.e. of a certain size). The (arbitrary) threshold chosen was 1 standard deviation for Monday’s returns.

FTSE 100 returns on Tuesdays when Monday was up-down (1SD filter)

It can be seen that limiting the analysis of Tuesday returns to just large movements on Monday (i.e. beyond 1 standard deviation) does help the reversal theory. In this case, if the market rises on Monday, then on average it falls the following day (albeit a pretty small average fall), and if the market falls on Monday, the market rises (fairly strongly) on the Tuesday.

Let’s now look at how the theory has been holding up in recent years.

Recent years

The following chart is similar in design to the previous charts, but this time it plots the reversal results for the discrete years 2013 – 2016.

FTSE 100 returns on Tuesdays when Monday was up-down [2013-2016]

First, when the market is up on Monday, all four of the past four years has failed to support the reversal theory as Tuesday has followed with positive returns as well. When Mondays are down, in three of the past four years Tuesdays have seen positive average returns (the exception being 2015).

Exploiting the reversal effect

OK, so how to exploit this?

The following chart plots the cumulative value of a portfolio that invests in the FTSE 100 just on Tuesdays when the previous day saw negative returns. For the rest of the time it is in cash.

In the 2013 study a variant portfolio was also considered, that as well as going long Tuesdays following negative Mondays also went short Tuesdays following positive return Mondays. There’s currently not much point in considering this as the reversal effect is not working for positive Mondays.

So, instead the variant second strategy studied here is as above (i.e. long Tuesday following a negative Monday) but with a 1 standard deviation filter applied to the Monday return (i.e. the strategy only goes long on Tuesday if the Monday negative return is a greater than 1 standard deviation return).

Strategies exploiting the Tuesday reversal effect [2000-2016]

Since 2000 it can be seen that the simple long Tuesday strategy out-performs the benchmark buy-and-hold FTSE 100 portfolio. The variant 1SD strategy only marginally out-performs the simple long Tuesday strategy, but does so with with a greatly reduced volatility.


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New 2017 edition of the Almanac just published


The new edition of the Almanac, The Harriman Stock Market Almanac 2017, has just been released.

The Almanac is a unique reference work providing traders and investors with the data to tackle the markets in the year ahead.

The 2017 edition is packed with new research. New strategies and studies appearing in the Almanac for the first time include-

New research

  • World’s Simplest Trading System ­ a simple trading system based on moving averages with an impressive performance.
  • Construction Sector 4M Strategy ­ exploits a seasonality anomaly of the construction sector.
  • Sell In May Sector Strategy ­ how to exploit the Sell in May effect with sectors.
  • Turn Of The Month Strategy ­ all the market’s gains occur in just six days around the turn of the month.
  • January Barometer ­ do the first five trading days of the year predict the full year?
  • Odd/even weeks ­ the market in odd weeks greatly out-performs that in even weeks.
  • Santa Rally ­ does a Santa Rally exist for shares and, if so, when does it start?
  • Santa Rally Portfolio ­ the 10 stocks that have had positive returns over the two-week Santa Rally period for every year since 2007.
  • Sell in May and come back…when? ­ if you sell in May when should you come back into the market?
  • Up/Down ratio ­ analysis of the correlation between the ratio of up/down days in a year and the overall annual return of the FTSE 100 Index.
  • Solar eclipse ­ do solar eclipses affect stock markets?
  • Dividend payment calendar ­ analysis of when FTSE 100 companies pay dividends throughout the year.
  • FOMC cycle ­ the equity premium in the US and worldwide is earned entirely in weeks 0, 2, 4 and 6 in FOMC cycle time.
  • The psychology of drawdowns ­ why investors may almost always feel a prevailing sense of loss.
  • Do European stocks follow the US on a daily basis? ­  analysis of the correlation of EuroSTOXX and S&P 500.
  • Fed rate cycle ­ analysis of the relationship between the Fed rate cycle and UK equities.
  • UK bank rate since 1694 ­ analysis of Bank of England base rate changes over the last three centuries.

Order your copy now!


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Day of the week grid

We have previously looked at data to see if there are any discernible patterns in market returns by day of the week. The following table presents another way of studying this.

The table shows the daily returns of the FTSE 100 Index for every day so far in 2016 (up to last Friday, 28 Oct). Positive returns are highlighted in green, negative returns in red. (White cells indicate a market holiday.)

Day of the week grid [2016 wk43]


  1. So far in 2016 the longest run of positive (or negative) returns for a day started in the 10th week of the year when day returns for eight consecutive Wednesdays were positive.
  2. For 11 weeks, the day returns on Fridays were the opposite sign to that on the previous day (Thursday). This run ended last Friday (when both Thursday and Friday saw positive returns).

Other articles looking at returns on days of the week.

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The Stock Market in November

November tends to be one of the quieter month for shares. After the sometimes dramatic moves in September and October, and before the traditional end-of-year rally in December, investors seem to take a pause in November. The month currently has the lowest volatility of monthly returns of any month in the year. Of course, this year may be different with the US presidential elections this month.

As can be seen in the accompanying chart, the market used to be strong in November for many years prior to 2005, but since then the market has been more likely to fall than rise in the month and has seen an average month return of -0.6%.

Monthly returns of FTSE All Share Index - November (1984-2015)

An average November

As can be seen in the following chart, on average the market tends to rise the first four days of the month, this could be influenced by investors buying into the market anticipating the strong six-month period of the year November to April (the Sell in May effect). After that the market then gives up those gains over the following few days, rises again, falls back, until finally increasing quite strongly over the final seven trading days of the month.

FTSE 100 average month chart for November [1984-2015]


In the last ten years the FTSE 350 shares that have performed best in November have been Babcock International Group [BAB], Compass Group [CPG], CRH [CRH], BT Group [BT.A], and Greene King [GNK]; Babcock, Compass and CRH have only had negative returns in November in one year since 2006. An equally-weighted portfolio of these five shares would have out-performed the FTSE 350 index by an average of 5.2 percentage points each year since 2006. While the FTSE 350 shares with the worst November performance over the last ten years have been Vedanta Resources [VED], Royal Bank of Scotland Group (The) [RBS], Tullett Prebon [TLPR], Ashmore Group [ASHM], and Standard Chartered [STAN].

Elsewhere, November has been a strong month for gold and weak for oil and GBPUSD.


This is a busy month for interim results: 64 companies from the FTSE 350 make their announcements this month.

Dates to watch for this month are: 1 Nov – two-day FOMC meeting starts, 3 Nov – MPC interest rate announcement at 12 noon, 4 Nov – US Nonfarm payroll report, 8 Nov – US Presidential Election, 24 Nov – Thanksgiving Day (US), NYSE closed, and 30 Nov – FTSE 100 quarterly review.

The big event this month will obviously be the US presidential election on 8 November. Analysis of the impact of these presidential elections on the UK market since 1972 shows that on average UK shares tends to trade stronger as the election day approaches, and then tails off in the few days following the election. The strongest day of the period has been the election day itself.

Further articles on the US presidential elections.

Article first appeared in Money Observer

Further articles on the market in November.

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Shares that like November

Shares that have been strong November

The following table lists the five FTSE 350 shares that have the best returns in November over the last ten years. For example, Babcock has an average return of 4.6% for the month of November. Each stock has risen in at least eight of the past ten years in November.

Company TIDM Avg(%)
Babcock International Group 4.6
Compass Group 4.5
CRH 4.3
BT Group 5.3
Greene King 4.8

A portfolio of these four stocks would have out-performed the FTSE 350 Index in November in nine of the last ten years with an average out-performance of 5.2 percentage points each November.

Shares that have been weak November

The following table lists the five FTSE 350 shares that have the worst returns in November over the last ten years. For example, Vedanta Reseources has an average return of -10.5% for the month of November. Each stock has fallen in at least eight of the past ten years in November.

Company TIDM Avg(%)
Vedanta Resources -10.5
Royal Bank of Scotland Group (The) -8.7
Tullett Prebon -7.8
Ashmore Group -5.3
Standard Chartered -3.7

A portfolio of these five stocks would have under-performed the FTSE 350 Index in November in eight of the last last ten years with an average under-performance of 6.7 percentage points each November.

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30 years since Big Bang

In the early 1980s the Office of Fair Trading brought a case against the London Stock Exchange, citing a range of restrictive practices which included:

  • fixed minimum commissions for stock trades
  • separation of brokers (who acted as agents for customers) and jobbers (market makers)
  • foreign membership of the stock exchange was not allowed

As a result the Exchange changed its rules which came into effect on 27 October 1986 (30 years ago today).

The effect on the financial industry in the UK – especially the City in London - was dramatic, such that this process of de-regulation is also referred to as Big Bang.

One of the greatest changes was the acquisition of many established City firms by foreign (mainly American) banks. This led to great debate of something called the Wimbledon Effect – i.e. whether an economy needs strong domestic competitors or if it can thrive by merely providing the forum for foreign-owned institutions.

Overall, London has thrived as a financial center since Big Bang and the deregulation has been seen as beneficial for financial markets. Although in 2010 Nigel Lawson, the Chancellor in 1986, admitted that the global financial crisis starting in 2007 was an unintended consequence of Big Bang. The problem being that previously investment banks had been careful with their own money, but merger with high street banks gave them access to depositors’ funds. and incorporation as limited liability companies removed the personal risk for managers (the principal–agent problem).

Below is an extract taken from George G. Blakey’s magisterial A History of the London Stock Market 1945-2007 to give a flavour of the market in 1986, the year of Big Bang.

Markets opened the New Year with a broad advance, but after hesitating on the political upset created by the Westland affair, which led to the resignation of two Cabinet ministers, Michael Heseltine and Leon Brittan, and a 1% increase in base rates to steady the pound after a sharp drop in the oil price, they recovered to close the month at record levels. There was no doubt that sentiment was aided by the sight of predators being willing to compete with each other and pay ever higher prices for what had once been thought of as rather dull companies. Thus Imperial Group and Distillers went for £2.5 billion each, some 25% above the opening bids, in hard-fought and no holds barred contests between determined bidders.

Markets were under something of a cloud in November and December as one scandal after another came to light. First of all Geoffrey Collier, a senior executive at Morgan Grenfell, resigned after insider dealing allegations. Then US arbitrageur, Ivan Boesky, who had been an active participant in many of the year’s big bids in the UK, was fined $100 million by the SEC. After weeks of rumours, December saw a DTI investigation ordered into the Guinness takeover of Distillers, closely followed by the revelation that Guinness had “invested” $100 million in Boesky’s arbitrage pool of funds. On the last day of the year, Roger Seelig, the Morgan Grenfell executive who had looked after the Guinness bid, resigned from his post at the bank.

Although these events were truly exceptional in the light of the high standing of the persons and the companies involved, they did not prevent a good Christmas rally developing in a market which also had to absorb the £5.6 billion offering from British Gas. The advent of dual capacity and automated quotations with Big Bang in October seemed to have no particular influence on the course of markets at the time. The FT 30 closed the year at 1313.9, well below its peak, but still a gain of 15.5%, while the broader- based All Share and FTSE were up 20% and 23.5% at 835 and 1679 respectively. Government Securities were up a modest 1.25% at 83.62. The Dow recorded a gain of 22.5% closing at 1896.


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CAPS Portfolio

A fun Quartz article found that a portfolio comprised of U.S. companies whose names were all upper case (e.g. NVIDIA) had out-performed the S&P 500 Index in 2016. The article’s explanation: confident companies have confident names!

How would such a portfolio fare in the UK?

The following table lists the 14 FTSE 100 companies with (almost) all upper case names. Included in the table are the returns from the beginning of 2015.

Company TIDM Rtn (from 2015)
BP BP. 39.9
CRH CRH 36.8
RSA RSA 31.2
DCC DCC 18.5
FTSE 100 UKX 12.4
BAE Systems BA. 8.2
TUI AG TUI -15.0
BT BT.A -17.8
ITV ITV -38.4

And the following chart plots the performance of an equally-weighted portfolio of the 14 upper case companies benchmarked against the FTSE 100 Index.

CAPS portfolio

As in the US case – it works!

Why do investors bother with anything more complicated?

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Trading days around US presidential elections

How does the UK market trade in the days around US presidential elections?

US presidential elections are held every fours years on the Tuesday following the first Monday in November (hence they are always between 2nd and 8th November). The newly elected president takes office at midday on Inauguration Day (20 January the following year).

In 2016 the US presidential election will take place on 8 November.

The table below shows the results of analysing the FT All-Share index for the 9 days around each US election since 1972.

  • Days 1-4: are the four trading days leading up to the election
  • Day 5: is the election day
  • Days 6-9: are the four trading days following the election
Day 1 2 3 4 5 6 7 8 9
Proportion of days up(%) 45 73 64 55 64 55 45 55 45
Average daily return(%) 0.56 0.33 0.39 0.36 0.64 -0.18 -0.49 0.29 -0.39
Standard deviation 2.45 0.66 1.11 1.05 1.35 0.95 2.09 1.17 1.28

The average return for each day is shown in the chart below.

FTSE All-Share around US presidential elections [1972-2012]

As can be seen, the UK market tends to trade stronger in the four days before the election, and is weaker in the few days following the election. The strongest day of the period has been the election day itself.

The above is an extract from the Harriman Stock Market Almanac.

See also: other articles on politics and markets.

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