By midday, shares had dropped -7.2% to $12.80.
Over the three months to March, Waltham, Mass.-based ImmunoGen reported a net loss of 44 cents a share compared to losses of 2 cents a share in the year-ago quarter. Analysts surveyed by Thomson Reuters had forecast a net loss of 27 cents a share.
Revenue tumbled to $6.88 million from $25 million a year earlier, missing estimates of $13.28 million.
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