* Futures up: Dow 68 pts, S&P 7 pts, Nasdaq 20.5 pts
By Sruthi Shankar
Nov 21 (Reuters) - U.S. stock indexes were set to open higher on Tuesday, as upbeat results from some retailers and cyber security firm Palo Alto helped pre-market sentiment.
* Palo Alto gained 9 percent after higher demand for its cloud-based services helped the firm beat revenue and profit estimates.
* Urban Outfitters rose more than 5 percent, while Dollar Tree was up 3 percent after posting their quarterly reports.
* Lowe's fell slightly even as the second largest U.S. home improvement chain reported strong sales and profit on higher demand for supplies and rebuilding material after hurricanes struck several parts of the country.
* Signet Jewelers tanked 16 percent after reporting weak same-store sales and a surprise quarterly loss.
* Wall Street closed higher on Monday, with the merger of two mid-size chipmakers lifting tech shares and a broker upgrade for Verizon boosting telecoms stocks.
* As third-quarter earnings wind down and no major economic data scheduled, trading volumes were thin and expected to get even quieter in the run-up to the Thanksgiving holiday.
* Federal Reserve Chair Janet Yellen said on Monday she would resign her seat on the Fed's Board of Governors once Jerome Powell is confirmed and sworn in to replace her.
* At an event later in the day, Yellen is expected to answer questions on her term atop the central bank and the direction of policy and Wall Street oversight in the years ahead.
* A report by the National Association of Realtors due at 10:00 a.m. ET (1400 GMT) is likely to show existing home sales increased 0.7 percent in October.
* Oil prices rose ahead of an OPEC meeting next week at which major crude exporters are expected to extend production cuts, though rising U.S. output capped gains.
* AK Steel rose about 5 percent after Credit Suisse upgraded the stock to "outperform".
Futures snapshot at 7:02 a.m. ET:
* Dow e-minis were up 68 points, or 0.29 percent, with 21,660 contracts changing hands.
* S&P 500 e-minis were up 7 points, or 0.27 percent, with 135,936 contracts traded.
* Nasdaq 100 e-minis were up 20.5 points, or 0.32 percent, on volume of 23,656 contracts. (Reporting by Sruthi Shankar in Bengaluru; Editing by Bernard Orr)