* Existing home sales data on tap
* Goldman cuts Boeing to sell rating
* Valeant, Salix agree to merger deal
* Futures: Dow off 35 pts, S&P off 4 pts, Nasdaq up 1 pt
By Chuck Mikolajczak
NEW YORK, Feb 23 (Reuters) - U.S. stock index futures dipped on Monday, after the Dow and S&P closed at records on the heels of an agreement by euro zone finance ministers to extend Greece's bailout by four months provided it draws up a list of reforms.
* Greece will present its economic reform plans on Monday to seal the euro zone financial lifeline, but the government drew criticism from a veteran leftist and ruling party member that the deal let voters down. The deal is conditional on Greece's European and IMF creditors accepting the reform list.
* The equity market gains led each of the three major Wall Street indexes to their third weekly advance on Friday, with the Nasdaq on an eight-session winning streak as it closed in on the 5,000 mark for the first time in nearly fifteen years.
* Existing home sales data is due at 10:00 a.m. (1500 GMT), the first in a flurry of economic reports this week that will help investors gauge the strength of the housing sector.
* Canada's Valeant Pharmaceuticals International Inc agreed to acquire gastrointestinal drugmaker Salix Pharmaceuticals Ltd in an all-cash deal valued at about $10.1 billion, the companies said on Sunday. U.S. listed shares of Valeant gained 6.2 percent to $184 while Salix slipped 0.8 percent to $156.55 in premarket trading.
* Asahi Kasei Corp, a Japanese chemicals maker, said it would buy Polypore International Inc's energy storage segment for $2.2 billion, as it seeks to expand in the energy and environment business. Polypore shares jumped 13.1 percent to $59.90 before the opening bell.
* Home Loan Servicing climbed 7.9 percent to $18.09 in premarket after the company agreed to be acquired by New Residential Investment Corp for about $1.3 billion. [ID:nASB097HM}
* Dow component Boeing fell 1.8 percent to $155.49 after Goldman Sachs cut its rating on the aerospace company to "sell" from "neutral. "
* European shares edged up in the wake of the Greece deal, although a slightly disappointing German business morale survey held gains in check.
* Japan's Nikkei 225 stock index hit a 15-year high, though MSCI's broadest index of Asia-Pacific shares outside Japan slipped 0.3 percent as many countries in the region returned from Lunar New Year holidays.
Futures snapshot at 7:35 a.m. EST (1235 GMT):
* S&P 500 e-minis were down 4 points, or 0.19 percent, with 70,362 contracts changing hands.
* Nasdaq 100 e-minis were up 1 point, or 0.02 percent, in volume of 10,590 contracts.
* Dow e-minis were down 35 points, or 0.19 percent, with 13,272 contracts changing hands. (Editing by Bernadette Baum)