AmerisourceBergen Corp said on Monday its Chief Financial Officer Michael DiCandilo had resigned to pursue other interests, effective immediately, sparking at least one broker downgrade and sending its shares down more than 3 percent.

The nation's third-largest drug wholesaler said that Tim Guttman, AmerisourceBergen's corporate controller since 2002, will become acting CFO immediately.

Baird Equity Research quickly downgraded the stock to neutral from outperform.

We weren't expecting this transition, and it comes on the heels of AmerisourceBergen's first quarterly EPS miss in over four years. CFO leadership transition follows change at CEO position last July, and other headwinds; we're moving to sidelines, Baird Equity Research analyst Eric Coldwell wrote in a note to clients.

AmerisourceBergen shares were down about $1.26, or 3.2 percent, at $37.34 in morning trading on the New York Stock Exchange.

Guttman was previously vice president of finance of Syncor International, and held financial planning and financial services managerial positions at Disney Consumer Products, Pizza Hut Inc and PepsiCo Inc. Guttman started his career as a certified public accountant with accounting firm Deloitte & Touche.

AmerisourceBergen has hired an executive search firm to manage the recruitment of a new CFO.

The company said it still expects fiscal 2012 diluted earnings per share to be in the range of $2.74 to $2.84. It anticipates flat to modest revenue growth and operating margin growth in the high single-digit to low double-digit basis points range. It reiterated its forecast for free cash flow of $700 million to $800 million, which includes capital expenditures in the $150 million range.

The company said it expects to spend about $400 million to repurchase its stock in fiscal 2012, subject to market conditions.

(Reporting By Debra Sherman; Editing by Maureen Bavdek)