Duchenne muscular dystrophy company PTC Therapeutics Inc(NASDAQ:PTCT) and gene therapy play bluebird bio Inc(NASDAQ:BLUE) last week became the third and fourth biotechs this year to raise more than $100 million in IPOs, putting the total raised by the 20 companies that have gone public at about $1.2 billion.

PTC raised $125.6 million through the sale of 8.4 million shares at $15, which values the company at $335.2 million. PTC had proposed to sell 6.9 million shares at $13-$16.