* Allergan, Pfizer drop after biggest-ever healthcare deal
* Alcoa up on report of Elliott stake, boosts materials
* Mallinckrodt up after posting higher sales
* Indexes up: Dow 0.04 pct, S&P 0.09 pct, Nasdaq 0.15 pct (Updates to open)
By Abhiram Nandakumar
Nov 23 (Reuters) - U.S. stocks eked out small gains on Monday morning, helped by gains in materials and consumer stocks, as investors stayed cautious after last week's strong gains and ahead of Thanksgiving.
Five of the 10 major S&P sectors were higher, kept afloat by the 0.53 percent rise in the materials sector, boosted by Alcoa, and a 0.5 percent gain in consumer discretionary stocks.
Pfizer's shares fell 2 percent to $31.54, after the company said it would buy Allergan in a deal valued at about $160 billion, the biggest ever in the healthcare sector. Allergan fell 2 percent to $306.17.
The two stocks were the biggest drags on the S&P 500, while Pfizer was the second-biggest drag on the Dow. But healthcare stocks stayed positive, helped by a gains in insurers.
U.S. stock are coming off a strong week, when the S&P 500 recorded its best performance this year and the Dow Jones industrial average turned positive for the year.
"We're coming off a very strong performance, a market that has shown tremendous resilience and a strong propensity of 'coming back'," said Andre Bakhos, managing director at Janlyn Capital LLC in Bernardsville, New Jersey.
"Chances are, the bulk of the action will take place Monday and Tuesday and then they turn their machines off," said Bakhos, adding volumes were likely to be "very quiet" this week.
At 9:52 a.m. ET the Dow Jones industrial average was up 7.55 points, or 0.04 percent, at 17,831.36.
The S&P 500 was up 1.83 points, or 0.09 percent, at 2,091 and the Nasdaq Composite index was up 7.77 points, or 0.15 percent, at 5,112.69.
Crude oil prices pared back some losses after Saudi Arabia agreed to cooperate with other producers to stabilize prices. But, the S&P energy sector fell 0.27 percent.
The dollar hit a seven-month high on Monday on expectations that the Federal Reserve will raise interest rates next month.
Alcoa rose 4 percent $9.05 after CNBC reported that Elliott Management had taken a 6.5 percent stake in the company.
GameStop tumbled 15 percent to $33.37 after the video game retailer reported lower quarterly sales and profit.
Mallinckrodt jumped 8 percent to $65.87 after the biopharmaceutical company posted a jump in sales.
Advancing issues outnumbered decliners on the NYSE by 1,589 to 1,149. On the Nasdaq, 1,298 issues rose and 1,087 fell.
The S&P 500 index showed 18 new 52-week highs and four new lows, while the Nasdaq recorded 25 new highs and 30 new lows. (Reporting by Abhiram Nandakumar in Bengaluru; Editing by Savio D'Souza)