Author and Wharton Professor Jeremy Siegel says his biggest worry about the stock market is oil prices. Siegel tells CNBC that if oil prices level off, he thinks stocks will gain another 10% to 15% this year. He says he’s not worried about the threat of a government shutdown, or the big federal deficit. Siegel also says that turmoil in the Middle East and the impact on oil prices should be driving investors away from Treasury bonds, not to them, as has been the case lately, because of the potential inflation rising oil prices cause. Instead, they should look to “real” assets, like stocks.