Shares of Ironwood Pharmaceuticals Inc. are up in their IPO debut after the drug developer's offering priced below expectations.

Ironwood sold 16.7 million shares for $11.25 apiece late Tuesday, raising nearly $188 million.

The Cambridge, Mass., biotechnology company had expected shares to fetch between $14 to $16 each.

Ironwood is trading on the Nasdaq Stock Market with the symbol "IRWD." Its stock was recently up 31 cents, or 2.8 percent, at $11.56.