Something does not make sense. If anyone could ever be clssified as an insider surely Sanofi would be it. Negotiations are taking place, the result of which could have a marked impact on the share price. They will obviously know first-hand how these negotiations are proceeding. To undertake share transactions under these circumstances would surely contravene insider laws. This would be so obvious that their advisors in London would surely advise them as such. Also, even if they had decided to sell, would they not sell in round amounts?
In conclusion, have they really sold? or have the shares been transferred to an unrelated party?