Shares of DineEquity Inc. plunged 26 percent on Tuesday, a day after the casual dining chain announced that its chief financial officer had resigned effective immediately to “pursue other opportunities.”

The Glendale-based operator of IHOP and Applebee’s restaurants said after Monday’s market close that it will work with search firm Crist Kolder Associates to find a successor to Thomas Conforti. Controller Greggory Kalvin will serve as interim CFO.

DineEquity reported in July that it had swung to a loss in the second quarter due to charges related to buying and franchising the Applebee’s chain, which is underperforming its flagship IHOP chain. The company reported a net loss of $19.4 million ($1.42 per share), compared with net income of $14.1 million (82 cents) a year ago.

In the press release, Conforti had complimentary things to say about his six years at the company, and Chief Executive Julia Stewart complimented Conforti’s contributions.

DineEquity shares lost $6.20 to close at $17.77 on the New York Stock Exchange.