The $510.3 million Gilead Sciences Inc. will pay to take out YM BioSciences Inc. puts the deal in the top five transactions involving a Canadian biopharma company in the past five years.

Gilead (NASDAQ:GILD) will acquire YM (TSX:YM; NYSE-M:YMI) for $2.95 share, an 81% premium to YM's close of $1.63 on Tuesday, before the deal was announced. YM has 173 million fully diluted shares outstanding.