U.S. stocks ended flat on Monday after recent rally pushed major indexes near four-year highs.

All three major indexes settled barely changed from the previous session after trading in a very narrow range.[Hong Kong Company Registration Guide]

When the market closed, the Dow Jones industrial average slipped 3.56 points, or 0.03 percent, to 13,271.64. The blue-chip index has been lower in 15 of the last 17 Mondays.

The Standard & Poor's 500 edged lower 0.03 points to settle at 1,418.13 while the Nasdaq Composite Index dipped 0.38 points, or 0. 01 percent, to 3,076.21.

Stocks seesawed throughout the session as investors were cautious after the market gained for six straight weeks. Meanwhile, concerns over the European debt crisis again took the center stage.

It is expected that the European Central Bank (ECB) would decide to intervene bond markets of European countries, helping to push down borrowing costs.

Speculations gained more steam after German Chancellor Angela Merkel reiterated her support for ECB President Mario Draghi's strategy to help the euro zone.

[Businesses Registration]However, Germany's central bank warned that the ECB should not share the "solvency risks" in the euro zone, adding uncertainties to the European debt crisis.

What also caught investors' attention is that the U.S. Federal Reserve will begin a two-day monetary policy meeting on Tuesday. Investors still expected that the U.S. central bank would launch further monetary stimulus policies.

Among stocks in focus, Apple jumped 2.63 percent to settle at another historic high of 665.15 dollars per share. Meanwhile, the tech giant officially became the most valuable company in the U.S. history with a market value of 623.5 billion dollars, surpassing Microsoft's peak value of 618.9 billion dollars set in December 1999 during the tech bubble.[Hong Kong Company Formation & Registration]

Social media company Facebook, however, hit a new low of 18.75 dollars per share in early trading, less than half of its issuing price of 38 dollar per share, before rebounding to 20.01 dollars on the close.