Many biotech stocks have generated incredible returns in recent years, but which are the best biotech stocks of the 21st century? This will exclude companies that haven’t traded publicly since the turn of the century or have market caps below $250 million, which weeds out many biotechs. Of the ones that survived those cuts, Acorda Therapeutics (NASDAQ: ACOR), Gilead Sciences (NASDAQ: GILD), and Celgene (NASDAQ: CELG) stand at the top of the list. Here’s how these three became the best biotech stocks of the century (so far).