The doughnut chain does not have any obvious suitors, but its business has become more attractive recently.
Krispy Kreme's so-called "poison pill" plan limits the way the company's previous operating losses and other credits could be applied to future taxes if there were a change of ownership. As of the beginning of 2012, the company had a federal net operating loss carryforward of approximately $240 million, as well as other credits that could be carried forward in the future.
The plan will expire in 2019.
Krispy Kreme, headquartered in Winston-Salem, N.C., sells doughnuts in over 730 locations around the world.
Shares fell 43 cents, or 3.6 percent, to $11.39 in midday trading.