Antigenics (AGEN) on Friday put its emphatic exclamation mark on the exploding biotech IPO market, pricing 3.5 million shares at $18 and then watching them skyrocket $43.375 (241 percent) to $61.375 on 5.2 million shares. The Phase II developer of heat shock proteins was valued at $1.5 billion at the close of its first day of trading.

Friday also saw Sequenom (SQNM) hurdling through the $2 billion market cap barrier after floating 5.25 million IPO shares at $26 to raise $136.5 million on Tuesday. Investors tripped over themselves to buy in the secondary market, bidding SQNM up to $95.375 and valuing the company at $2.25 billion; nearly seven times the $331 million take out price that PE Biosystems (PEB) is paying for another genomics play, Third Wave Technologies (see BioCentury, Jan. 31).

AGEN and SQNM eclipsed even their stepped-up expectations. SQNM, which is developing single nucleotide polymorphism (SNP) detection technology, originally filed in November to raise up to $70 million, and last month amended the offering to sell 5 million shares at $23-$25. AGEN filed to raise up to $46 million in November, and then amended the filing last month to sell 3 million shares at $14-$16.

IPO buffet

The market now will belly up to a new smorgasbord of paper, as DrugAbuse Sciences, InterMune, Tanox and Rigel filed IPOs. If the deals go off at the top end of the range, the group would raise $383 million.