US STOCKS-Wall Street dips on global worries; oil stocks trickle lower
* Oil prices fall after rising for eight straight weeks
* Apple biggest drag on S&P 500, Nasdaq
* Indexes: Dow down 0.4 pct, S&P down 0.3 pct, Nasdaq flat (Updates to mid-afternoon)
By Noel Randewich
May 11 (Reuters) - U.S. stocks were down on Monday afternoon due to worries about Greece's precarious financial condition and slowing growth in China, while energy stocks fell on weaker oil prices.
U.S. stocks, which rallied on Friday on a strong jobs report, have been trading at historically expensive valuations, fueled by ultra-low borrowing costs.
The S&P 500 is trading at 17 times expected earnings, compared with its historical 10-year median average of 15, according to Thomson Reuters StarMine data.
April payroll data out last Friday indicated U.S. economic growth was picking up, but not enough to raise concerns about an earlier-than-expected interest-rate rise by the Federal Reserve.
"People are still concerned about whether we will have a liftoff in the fall or not. That's the big driver," said Michael Matousek, head trader at U.S. Global Investors Inc in San Antonio. Continuación...