In November, ImmunoGen Inc. decided to do a secondary instead a PIPE because it thought it would do better with the former, raising more money and taking less of a discount.

"How wrong we were," said Mitchel Sayare, IMGN's chairman and CEO. "At the end of December we were told too many deals were trying to close in the market overall and on the bankers' advice we delayed. It was during that period that the market began to turn."

The company also ran into investors cautious about monoclonal antibodies and cancer. "Both are areas in which there have been substantial disappointments - and we combine them," he said. "Though we've hit our milestones, people were more reserved."

Heavy discount

The deal had a weak book, with a dominant institution that set the price, leaving the bankers very little leverage, said Sayare. IMGN took a 33 percent discount and raised $12.3 million.