(Corrects name of NAFTA in second graph and name of Sears Holding Corp in paragraph 7)
* Eyes on Canada following U.S.-Mexico NAFTA deal
* Nasdaq, S&P eke out new highs
* Best Buy slides on weak online sales, disappointing forecast
* Sears Holding jumps as Amazon partnership expands
* Indexes up: Dow 0.15 pct, S&P 0.07 pct, Nasdaq 0.21 pct
By Stephen Culp
NEW YORK, Aug 28 (Reuters) - The S&P 500 and the Nasdaq edged up to record highs for the third consecutive session on waning trade jitters that have vexed the markets for much of the year.
On the heels of the United States-Mexico agreement to overhaul the North American Free Trade Agreement (NAFTA), focus shifted to United States' trading partner to the north as Canada's top trade negotiator joined her Mexican and U.S. counterparts in Washington in a bid to remain in the trilateral pact.
All three major U.S. indexes were marginally up in a session of back-and-forth trading as investors debated whether to take profits or ride the market's momentum.
Technology companies led the advance, offset by declines utilities, materials and telecom sectors.
"People trying to figure out whether it pays to stay in (the market) or would it be prudent to take profits now that we got the bump on recent positive trade news," said Chuck Carlson, chief executive officer at Horizon Investment Services in Hammond, Indiana. "Is the next news on the trade front going to be negative? Should they sell or ride the momentum right now?"
Luxury retailer Tiffany & Co reported better-than-expected second-quarter results and raised its full-year profit forecast. The stock trimmed early gains, and is now up 0.1 percent.
Sears Holding Corp shares jumped 13.5 percent as its Auto Center partnership with Amazon.com expanded, its services now available nationwide. The partnership was first announced in May.
Yum China Holdings rose 3.1 percent following a Wall Street Journal report that the fast food operator rejected a buyout.
The Dow Jones Industrial Average rose 37.92 points, or 0.15 percent, to 26,087.56, the S&P 500 gained 2.11 points, or 0.07 percent, to 2,898.85 and the Nasdaq Composite added 16.73 points, or 0.21 percent, to 8,034.63.
Of the 11 major sectors of the S&P 500, five were in positive territory, with real estate and technology posting the biggest percentage gains.
Among losers, shares of Best Buy Co Inc sank 4.8 percent after the electronics retailer reported a drop in online sales growth and provided underwhelming third quarter profit guidance.
Campbell Soup Co dipped 1.6 percent after a New York Post report that the soup maker does not plan to sell itself.
Tesla Inc stock extended its decline, falling 1.4 percent in the wake of chief executive Elon Musk's decision to abandon his take-private scheme. Separately, broker Canaccord Genuity said it expects the electric automaker to miss its Model 3 production targets.
Declining issues outnumbered advancing ones on the NYSE by a 1.23-to-1 ratio; on Nasdaq, a 1.03-to-1 ratio favored advancers.
The S&P 500 posted 41 new 52-week highs and 1 new low; the Nasdaq Composite recorded 90 new highs and 17 new lows.
Reporting by Stephen Culp Editing by Chizu Nomiyama