* Boeing top drag on Dow on Trump's tweet

* Intralinks jumps on deal to be bought by Synchronoss

* Dow down 0.1 pct, S&P down 0.05 pct, Nasdaq flat

(Updates to open)

By Yashaswini Swamynathan

Dec 6 (Reuters) - Wall Street was slightly lower on Tuesday morning, as gains in financial stocks failed to make up for losses in energy stocks following a drop in oil prices.

Brent crude prices fell 2.5 percent, the first decline in five days, after data showed an increase in output from major producers, just days after OPEC and Russia agreed to a production cut. (O/R)

The S&P 500 energy sector (.SPNY) fell 1.07 percent, weighed down by Exxon (XOM.N) and Chevron (CVX.N) . Oil prices had risen more than 18 percent since last Wednesday when the producers agreed to limit output.

Investors are now shifting their focus to the upcoming Federal Reserve policy meeting next week, where traders see a 92 percent chance of an interest rate hike.

U.S. stocks have climbed since the Nov. 8 election, driven by expectations of significant economic stimulus and cuts in corporate taxes and regulations under President-elect Donald Trump.

Financials (.SPSY) provided the biggest boost to the S&P 500 on Tuesday, but failed to counter the impact of weaker oil.

Five of the 11 major S&P sectors were lower.

At 9:45 a.m. ET the Dow Jones industrial average (.DJI) was down 18.46 points, or 0.1 percent, at 19,197.78.

The S&P 500 (.SPX) was down 1.03 points, or 0.05 percent, at 2,203.68 and the Nasdaq Composite (.IXIC) was down 0.05 points, at 5,308.84.

Boeing's (BA.N) shares fell 1.1 percent to $150.53, after Trump tweeted that costs of the planemaker's 747 Air Force One aircraft were "out of control" and that the order should be canceled. The stock was the biggest drag on the Dow.

Intralinks (IL.N) soared 16.2 percent to $13.10 after Synchronoss Technologies (SNCR.O) said it would buy the cloud-based business software provider for $821 million, representing a 15.4 percent premium. Synchronoss shares were off about 12 percent.

Advancing issues outnumbered decliners on the NYSE by 1,429 to 1,189, for a 1.20-to-1 ratio on the upside. On the Nasdaq, 1,186 issues fell and 1,093 advanced for a 1.09-to-1 ratio favoring decliners.

The S&P 500 index showed 18 new 52-week highs and no new lows, while the Nasdaq recorded 100 new highs and 5 new lows.