WaMu’s new CEO Alan Fishman gets $20 million pay package after only Seventeen Day on the Job !

Washington Mutual’s new chief executive will receive a salary and incentive package worth more than $20 million through 2009 for taking the helm of the battered Seattle-based bank.

The pay package details were released by the bank in a regulatory filing at the close of business Thursday — a day that saw the company’s stock dip below $2.

Shares of the company (NYSE: WM) closed at $2.83, up about 22 percent compared with Wednesday’s close. It briefly traded as low as $1.75.

Alan Fishman, 62, who replaces ousted chief executive Kerry Killinger, will receive an annual base salary of $1 million, a sign-on bonus of $7.5 million and an annual bonus of 365 percent of his base salary, or of $3.65 million. WaMu declined to comment on the pay package.

If he stays for the full year, he’ll receive a long-term incentive award of no less than $8 million, according to the Security and Exchange Commission filing.

Fishman also will receive options to purchase 5 million shares of the company and 612,500 restricted shares, which will vest at an annual rate of 33.3 percent over three years if he’s still employed. The options will have a term of seven years and will vest based on his service and company performance, although a quarter of those shares, or 1.25 million, will vest after one year regardless of performance.

If Fishman is fired or resigns as a result of “constructive termination,” he’ll receive a golden parachute within 10 days, worth 2.5 times his current base salary and his annual bonus of the preceding year.

Killinger’s annual pay has been estimated by various news sources at about $15 million.

Also on Thursday, WaMu made the unusual move of releasing mid-quarter performance figures. The company expects its loan loss provisions to drop $1.4 billion in the third quarter to about $4.5 billion.