* Retailers down in premarket after earnings
* AstraZeneca investor protests spurning of Pfizer bid
* Aeroflex jumps, to be acquired by Cobham for $1.46 bln
* Futures off: Dow 9 pts, S&P 1.3 pts, Nasdaq 1 pt (Adds Dick's earnings, Morning Call link, updates prices)
By Chuck Mikolajczak
NEW YORK, May 20 (Reuters) - U.S. stocks were poised for a flat open on Tuesday, after the S&P 500 advanced for two straight days and investors assessed some of the final corporate results of earnings season.
* Home Depot lost 1.3 percent to $75.52 in premarket trade after the home improvement retailer reported lower-than-expected quarterly sales as its spring selling season got off to a slow start.
* Staples Inc tumbled 10.9 percent to $11.93 after the office supply retailer posted first-quarter earnings and forecast a decline in sales in the current quarter.
* Dick's Sporting Goods estimated current-quarter earnings way below analysts' average estimate and cut its full-year 2014 adjusted earnings and same-store sales growth forecasts due to weak demand for its golf and hunting products. Its shares tumbled 14.7 percent to $45.35 in premarket.
* Equities have pulled back since hitting their most recent record high May 13 as economic data has painted a mixed picture and failed to confirm an acceleration in the economy that many had hoped to see.
* S&P 500 e-mini futures shed 1.3 points and were roughly even with fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average e-mini futures lost 9 points and Nasdaq 100 e-mini futures shed 1 point.
* U.S.-listed shares of AstraZeneca advanced 1.9 percent to $71.97 in premarket after its twelfth largest shareholder, Schroders, joined a chorus of investor disapproval over its rejection of a takeover offer by Pfizer and urged it back into talks.
* Aeroflex Holding Corp jumped 24.9 percent to $10.38 before the opening bell. British aerospace and defense supplier Cobham is buying the U.S. communications equipment maker for $1.46 billion.
* U.S. stocks rose on Monday, as a rally in high-growth names among Internet and biotech shares sent the Nasdaq to a gain of nearly 1 percent and investors shrugged off recent concerns about stock valuations and the economy's growth prospects. (Editing by Bernadette Baum)