Updated from 6:44 a.m. EST.

NEW YORK (TheStreet) -- Here are 10 things you should know for Monday, Feb. 23:

1. -- U.S. stock futures look negative, although stocks ended last week at a record high.

European stocks were still riding their lift from Friday's debt deal between Greece and the rest of Europe.

2. -- The economic calendar in the U.S. on Monday includes the existing home sales report at 10 a.m.

3. -- U.S. stocks on Friday closed at record highs as Greece and the eurozone came to a debt deal.

The S&P 500 (SPY - Get Report) closed up 0.61% to 2,110.30. The Nasdaq (QQQ - Get Report) rose 0.63% to 4,955.96. The Dow Jones Industrial Average (DIA - Get Report) was up 0.86% to 18,140.44.

4. -- Canadian drugmaker Valeant Pharmaceuticals (VRX) has agreed to buy Raleigh, N.C.-based Salix Pharmaceuticals (SLXP) for $10.4 billion in cash, for a total deal worth $14.5 billion when Salix's debt is factored in. Valeant has bought several smaller drug companies, but last year failed in its attempt to buy Allergan (AGN - Get Report) . Salix's share price has risen 50% in three months over rumors of the company's acquisition by Valeant, Shire (SHPG) or another suitor.

In premarket trading, Valeant was up 5.6% to $183.02.

5. -- Janet Yellen will speak to the Senate Banking Committee on Tuesday, one of her two annual appearances before Congress to talk about the Federal Reserve's monetary policy. Fed watchers are speculating about when the Fed will raise interest rates, which could happen as soon as June.

6. -- Greece has struck a deal with the rest of Europe to manage its debt and to allow it to remain in the 19-country eurozone. The euro has substantially weakened over the past weeks -- down 6.5% in 2015. Greece's new left-wing government is facing pushback on the deal.

7. -- Apple (AAPL - Get Report) is investing $1.9 billion to build two new data centers in Europe, it said Monday. The renewable energy-powered data centers are planned to open in 2017 and will support Apple's online services. In a statement, Apple CEO Tim Cook described the project as "Apple's biggest project in Europe to date."

European sales made up 23% of Apple's revenue in the last quarter. Apple shares were up 0.2% in premarket trading, to $129.75.

8. -- President Obama is expected to veto legislation authorizing the Keystone XL oil pipeline, likely some time this week and perhaps as soon as Monday. Congressional Republicans have passed a bill to approve the pipeline but have not yet delivered it to the president.

The pipeline would connect the Canadian oil sands of Alberta to the Gulf of Mexico. The oil pipeline is in legal limbo, which further complicates oil prices. Oil has fallen sharply over the past eight months.

9. -- A large-scale, monthlong strike at oil refineries may further affect the price of oil. Strikes at refineries in Texas and Louisiana are impacting one-fifth of U.S. refineries. United Steelworkers and Royal Dutch Shell (RDS.A - Get Report) are having difficulty coming to labor terms for a new three-year contract.

The strike is the largest at oil refineries in 30 years.

10. -- The Labor Department will develop new rules for brokers and financial managers of retirement accounts, President Obama is expected to announce to an AARP meeting Monday. New fiduciary standards -- in which financial advisers are required to act in clients' best interest -- will likely be part of the new rules.

White House senior adviser Brian Deese said in a statement that the rule changes are designed to limit hidden fees and payments to financial managers.

-- Written by Nora Morrison

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Nora Morrison is an editor, writer and researcher on music, popular culture and business. She is an associate editor at TheStreet, and is on Twitter at No Ticker.