The following chart shows the impact on the FTSE 100 Index of a 10% move in the share price of each of the 20 largest companies in the index. [The reference level for the FTSE 100 is 6318.]
For example, if the share price of Shell fell (rose) 10% the impact on the FTSE 100 Index would be a fall (rise) of 49 points in the index.
Shares that like February
The following table lists the five FTSE 350 shares that have the best historic returns in February over the last ten years. For example, Fidessa has an average return of 14.9% for the month of February. Each stock has risen in nine of the past ten years in February.
| Company | TIDM | Avg(%) |
| Fidessa Group | FDSA | 14.9 |
| Imagination Technologies Group | IMG | 13.5 |
| Croda International | CRDA | 9.6 |
| Xstrata | XTA | 8.3 |
| Provident Financial | PFG | 7.0 |
A portfolio of these five stocks would have out-performed the FTSE 350 Index in every February over the last ten years with an average out-performance of 9.5 percentage points each February.
Shares that dislike February
The following table lists the five FTSE 350 shares that have the worst historic returns in February over the last ten years. For example, AstraZeneca has an average return of -3.5% for the month of February. Each stock has fallen in at least seven of the past ten years in February.
| Company | TIDM | Avg(%) |
| Greene King | GNK | -1.4 |
| AVEVA Group | AVV | -1.5 |
| Vodafone Group | VOD | -1.7 |
| BTG | BTG | -2.5 |
| AstraZeneca | AZN | -3.5 |
A portfolio of these five stocks would have under-performed the FTSE 350 Index in every February over the last ten years with an average under-performance of 3.3 percentage points each February.