Auction house Sothebys (NYSE:BID) has gained on main competitor Christie’s over the last year and looks set to turn its real estate holdings and financial services into additional sources of revenue, but Citi analysts Oliver Chen and Nancy Hilliker are still neutral on the stock over concerns about the nature of the auction business and Sotheby’s ability to deliver in emerging markets. Sothebys’ functions Sothebys (NYSE:BID) is the world’s second largest auctioneer after Christie’s, handling $4.3 billion in auctions in 2010 (with no other company seriously rivaling the pair), and the only one that is publicly listed. In addition to auctioning off…