Retail gasoline prices rose more than 25 cents in the Los Angeles metroplex after Exxon Mobil ( XOM) announced that production was cut at its 150,000 barrel-per-day refinery there, further heightening concerns over gasoline inventories. "Bullish inventory figures were the primary cause of this week's hike in energy prices, rather than the geopolitical issues that were in the news," Schenker said. As evidence of this, Schenker pointed to the difference between Thursday's $2.08 increase in crude prices -- spurred by inventory concerns -- and the smaller gain to end the week following the worries about Iran. "Daily volatility isn't important when analyzing trends in energy futures markets," Schenker said. "Look at what happens over a number of days, rather than only focusing on what happens in one trading day." Meanwhile, energy stocks were mostly stronger at the close of trading. The CBOE Oil Index was up 0.6% at 652.36. ConocoPhillips ( COP) rose 0.9%, Chevron ( CVX) traded 1.1% higher, and Exxon added 0.9%. Spectra Energy ( SE) was upgraded by BMO Capital Markets to outperform from market perform, and its stock gained 1.5% higher to $25.58. Shares of Dominion Resources ( DOM) were upgraded by A.G. Edwards to hold from sell, giving it a 7% lift to $25.82. Among downgrades, Trans Canada Pipelines ( TRP) was cut by BMO Capital Markets to market perform from outperform, sending the stock down 0.8% at $33.53.