US STOCKS-Wall St to open flat after two-day gain; Home Depot down
* 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.