With activist investor Carl Icahn bearing down, Nuance Communications Inc. has deployed a new line of defense that could be used to block the billionaire from strengthening his control over the speech recognition powerhouse.
The Burlington company behind Dragon software and Siri on the Apple iPhone enacted a plan Tuesday that would effectively prevent any outside investor from gaining 20 percent ownership of the firm.
It came 12 days after Icahn increased his stake in Nuance to 16 percent.
Nuance said the implementation of its stockholder rights plan — a tactic often referred to as a poison pill — was not prompted by any individual investor or group. But one analyst said it would throw a wrench into any effort by Icahn to assume control of the firm. Full story for BostonGlobe.com subscribers.
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