US STOCKS-Traders buy the Wall St dip, but nixed deals weigh
* Energy sector leads rebound in S&P 500
* Russia has 20,000 troops on Ukraine border -NATO
* Sprint, T-Mobile shares fall as Sprint drops bid
* Cognizant, Groupon shares down after results
* Indexes up: Dow 0.3 pct, S&P 0.3 pct, Nasdaq 0.3 pct (Updates to morning trading, recasts, adds comment)
By Rodrigo Campos
NEW YORK, Aug 6 (Reuters) - U.S. stocks rose in morning trading on Wednesday after buyers stepped in as the S&P 500 hit a more than two-month low, but concern about an escalation of the Russia-Ukraine conflict and two nixed deals weighed on sentiment.
Energy shares attracted a lot of the buying as Brent crude bounced from a 9-month low and the S&P energy index, down in seven of the previous eight sessions, jumped 1.3 percent to be the best-performing of the top ten industry sectors.
Futures traded lower before the open after NATO said Russia has around 20,000 combat-ready troops on Ukraine's eastern border and could use the pretext of a humanitarian or peace-keeping mission to invade. Continuación...