Oil has stocks on a slippery slope heading into the quarter-ending, holiday-shortened week.Investors are focusing on crude right now as it continues a relentless march higher. The steady drumbeat of bad news from the financial-services and housing sectors hasn't helped, either. "Markets are hanging on one issue: the price of oil," says Vinny Catalano, chief investment strategist at Blue Marble Research. Crude ended last week solidly above $140, and many people believe oil will have to break lower before stocks can make a good upward move. Oil and oil-services companies such as Exxon Mobil ( XOM), ConocoPhillips ( COP) and Halliburton ( HAL) will also be focal points as long as the market is watching the energy sector. "The momentum on this latest leg might tire out between here and $145," says Tom Bentz, director and senior energy analyst at BNP Paribas Commodity Futures. "Everybody's looking for $150 a barrel, so I wonder if we'll start to get a lot of speculation built in for $150 -- and sometimes, when everyone's looking for something, the market doesn't give it." Still, he adds: "It's an uptrend, and it doesn't look like it's ready to stop yet." Shares are on pace for a terrible June. Indeed, they ended lower last week, with the Dow tumbling 4.2% to 11346.51, the Nasdaq falling 3.8% to 2315.63 and the S&P 500 dropping 3% to 1278.38. One bit of relief as stocks limp lower: Monday is the last day of the second quarter. "I don't think there's a portfolio manager in the country, unless they're long energy and short financials, who doesn't want to start the new quarter," says Tony Dwyer, equity-market strategist at FTN Midwest Research.