Modest Advance for Wall Street

"Oil prices rise, [and] the markets rise, as demand for oil remains high, indicating that the global economy is still chugging along," said Paul Nolte, director of investments with Hinsdale Associates. "Oil prices decline and the markets rally, as lower oil prices will add to consumers' ability to spend. The markets are not really paying attention to oil prices."

Nolte warned, though, that rallies are starting to come "on lower volume and less participation than at any time since the August bottom."

Meanwhile, investors were waiting on a looming decision from the Fed on whether to lower lending rates. The Federal Open Market Committee convenes Tuesday for a two-day meeting, with an announcement expected Wednesday at 2:15 p.m. EDT.

Most economists are expecting a 25-basis-point reduction, which would be the second after the Fed kept its fed funds target rate at 5.25% for nine straight meetings, dating back to June 2006.

"The fed funds futures figure a 100% certainty of a rate cut this week," said Michael Sheldon, chief market strategist with Spencer Clarke. "The surprise is if the Fed cuts by a half-point or if they don't cut rates at all, which would be a major disappointment for the markets. However, there could be some alarm that the Fed knows something we don't, and that things could be much worse than we expect."