Acceleron's IPO of 5.6 million shares priced at $15 per share, bringing it $83.7 million before expenses and underwriting discounts. The Cambridge, Mass., had expected to sell 4.7 million shares for $13 to $15 each.
The underwriters of the IPO will have the option to buy another 837,000 shares.
Acceleron Pharma Inc. shares advanced $5.10, or 34 percent, to $20.10 while the broader markets were down.
The stock is listed on the Nasdaq Global Market under the symbol "XLRN."
Separately, Celgene Corp. will buy 666,667 shares for $15 each, giving Acceleron another $10 million. The companies are studying two drugs together.