* Caterpillar opens at a record high after brokerage upgrade
* Nasdaq biotech index on track for its worst day since Oct. 26
* GoPro plunges to new lows after Q4 sales warning
* Dow down 0.15 pct, S&P off 0.08 pct, Nasdaq up 0.1 pct (Changes comment, adds details, updates prices)
Jan 8 (Reuters) - The S&P 500 and the Dow were trading slightly lower on Monday, as losses in healthcare and financial stocks stalled Wall Street's strongest start to a year in a decade.
The benchmark S&P and the Nasdaq last week recorded its strongest first four trading days in a year since 2006, and the Dow industrials posted its best since 2003.
"The market was probably a little bit overbought, it was a big week for stocks in terms of strength and breadth, it's more of a pause," said John Brady, senior vice president at futures brokerage R.J. O'Brien & Associates in Chicago.
"The weakness might be there for a day or two, with some rotationary balancing, it won't take out much."
At 11:01 a.m. ET (1601 GMT), the S&P 500 was down 2.14 points, or 0.08 percent, at 2,741.01.
The Dow Jones Industrial Average was down 37.83 points, or 0.15 percent, at 25,258.04, while the Nasdaq Composite was up 6.80 points, or 0.1 percent, at 7,143.36. Both the indexes eked out new record highs briefly after open.
Investors are awaiting the fourth-quarter earnings reports to gauge the impact of recent tax cuts. The earnings season kicks off later this week, starting with big banks.
Shares of Bank of America, Goldman Sachs and Wells Fargo were down between 0.6 percent and 0.9 percent. Most big U.S. lenders have estimated one-off charges to their fourth quarter earnings on account of tax cuts.
The S&P healthcare index fell 0.81, declining most among the major S&P sectors on the first day of JP Morgan annual healthcare conference in San Francisco.
The Nasdaq biotech index fell 1.86 percent and was set for its worst day since Oct. 26, led by about 4 percent drop in Biogen and about 2.5 percent drop each in Celgene and Regeneron.
Caterpillar climbed 1.47 percent to open at a record high after JP Morgan upgraded the stock saying the tax overhaul could help construction business cycle extend into 2018.
Amazon rose about 1.23 percent after Credit Suisse hiked its price target on the online retailer's stock.
Nvidia gained about 3.13 percent after the graphics chipmaker announced partnership with Uber and Volkswagen as its artificial intelligence platforms expand into technology for self-driving cars.
GoPro shares hit record low after the company said it expected lower fourth-quarter revenue and would exit the drone business.
Declining issues outnumbered advancers on the NYSE by 1,557 to 1,211. On the Nasdaq, 1,760 issues fell and 1,044 advanced.
(Reporting by Sruthi Shankar in Bengaluru; Editing by Arun Koyyur)