UPDATE 3-Wal-Mart CEO pay fell last yr as profit missed goal

* Incentive pay $3.85 mln; down from $4.8 mln in prior yr

* Operating income "slightly below" incentive plan goal

* CEO: Positive same-store sales is "top priority this yr" (Adds details on salary, acquisition)

NEW YORK, April 18 (Reuters) - Wal-Mart Stores Inc (WMT.N) Chief Executive Mike Duke earned $18.7 million last year, down from $19.2 million the prior year, as the retailer's profit fell short of its goal.

Wal-Mart said in a regulatory filing on Monday that Duke's cash incentive payment for fiscal 2011 was $3.85 million, almost $950,000 less than his incentive pay for fiscal 2010.

The company said its overall performance last fiscal year was "slightly below" the goal set under its cash incentive plan.

"While our earnings performance exceeded our original guidance provided at the beginning of fiscal 2011, when our incentive goals were set, the sales performance of our Walmart US division was disappointing," the company said.

Duke's salary was $1.23 million in fiscal 2011, which ended on Jan. 31, up from $1.20 million in 2010.

Duke said in a separate statement that achieving positive same-store sales -- a key gauge of retail health -- was his "top priority this year". In February, the world's largest retailer said sales at its U.S. discount chain should improve as the year progresses. It has reported seven consecutive quarterly declines.

Wal-Mart is also trying to boost its business online, and said on Monday that it would acquire social media company Kosmix. [ID:nN18222348]

Wal-Mart shares were down 22 cents, or 0.4 percent, to $53.33 in Monday afternoon trade on the New York Stock Exchange. (Reporting by Martinne Geller; editing by Gunna Dickson, Tim Dobbyn and Bernard Orr)