Updated from 12:29 p.m. EDTShares of Affiliated Computer Services ( ACS) sank Monday after the company unexpectedly announced the departure of CEO and longtime employee Jeff Rich. ACS immediately named President and COO Mark King to the top post. Rich will enjoy a nice safety net, as he appears poised to form his own M&A firm. Shares of ACS recently traded down $3.46, or 6.3%, at $51.14 in after-hours trading after falling to as low as $50.78 Monday in volume that was more than six times its daily average in the past three months. Dallas-based ACS said Rich will leave the top post and his position on the board of directors to "pursue other business ventures" after 16 years with the IT services firm and six years as its CEO. But in a regulatory filing that outlined a generous departure package for Rich, ACS also mentioned the possibility of the executive starting an M&A advisory firm -- with his former employer as a client. "In the event Mr. Rich establishes an M&A advisory firm by Jan. 1, 2007, the company will retain such firm for a two-year period from its formation for $250,000 per year plus a negotiated success fee for completed transactions," the filing said. That's not the only connection Rich will retain with ACS. Rich will remain on the company's payroll and receive a salary of $820,000 a year through June 30, a lump-sum payment of $4.1 million, health benefits through Sept. 30, 2007, and limited administrative assistance through Sept. 30, 2006. ACS also will pay Rich for his vested options, with the payment determined by subtracting the strike price from $54.08, Thursday's closing price. His unvested options, valued around $4.6 million, will be terminated. Rich will remain an employee with ACS through June 30, assisting the company with an orderly transition of duties to his successor, according to an agreement between Rich and the company.