If I were a BP and wanted some inexpensive shares of a company that was about to deliver Phase 3 trial results and possibly have to sepend billions of dollars to buy the company,... why not buy a few million shares now for next to nothing and reduce the overall price considerably.

The news would send the price up big time so their investment would probably double overnight!

Pharmas don't typically speculate in the stock market like that.  Do you want to be the pharma exec who does what you suggest only to have the results fail?  Not good for his/her job security.  I think pharmas would like to wait as long as possible to derisk as much as possible.