* S&P 500 Q3 earnings expected to rise 4.9 pct, Reuters data
* Tesla down on delay in unveiling big rig truck to mid-Nov
* Viacom slips after Citi downgrades to "sell"
* Indexes up: Dow 0.05 pct, S&P 0.02 pct, Nasdaq 0.1 pct (Updates to open)
By Sruthi Shankar
Oct 9 (Reuters) - U.S. stocks eked out enough gains on Monday to push the Dow Jones Industrial Average and the Nasdaq Composite to fresh records ahead of the start of the third-quarter earnings season.
A boost to corporate profit could also come from President Donald Trump's proposed tax overhaul, hopes for which brightened last week after the U.S. House of Representatives approved a fiscal 2018 spending blueprint to help them advance an eventual tax bill.
"It appears that we have some investors follow-through with optimism on tax cuts and there was no bad news on geopolitical front," said Andre Bakhos, managing director at Janlyn Capital LLC in Bernardsville, New Jersey.
"Given where we in the market cycle, any stress in earnings ... by companies could become a speed bump."
With the stock market rallying for most of the year, the valuations for many stocks have risen above their long-term averages, and strong earnings reports would help justify those premiums.
Overall, earnings at S&P 500 companies are expected to have increased 4.9 percent in the third quarter, according to Thomson Reuters data, down from double-digit growth in the first two quarters of this year.
Two of the biggest Wall Street banks - JPMorgan Chase and Citi - kick off the quarterly results season proper on Thursday.
At 9:43 a.m. EDT the Dow was up 10.39 points, or 0.05 percent, at 22,784.06, the S&P 500 was up 0.58 points, or 0.02 percent, at 2,549.91 and the Nasdaq was up 6.52 points, or 0.1 percent, at 6,596.70.
The U.S. bond market is closed for the Columbus Day holiday.
Weak jobs numbers halted an eight-day winning streak for the S&P 500 on Friday, but the Nasdaq ended up for a ninth straight day.
Nine of the 11 major S&P indexes were higher, led by 0.38 percent gain in the energy index.
GE dipped 2.8 percent and was the top drag on S&P after the conglomerate said it gave activist investment firm Trian Fund Management a board seat.
Tesla was down 1.75 percent after the company pushed back the unveiling of the big rig truck until mid-November.
Viacom slipped more than 4 percent after Citigroup downgraded the media company's stock to "sell".
Medtronic dropped about 3 percent after the medical device maker said its second quarter 2018 earnings and sales would take a hit from hurricane Maria.
Advancing issues outnumbered decliners on the NYSE by 1,622 to 846. On the Nasdaq, 1,384 issues rose and 963 fell. (Reporting by Sruthi Shankar in Bengaluru; editing by Patrick Graham)