BP Prudhoe Bay Royalty Trust ( BPT) tumbled on news that BP ( BP) said it was shutting down its Prudhoe Bay oil field in Alaska due to a corroded pipeline and a small leak. BP Prudhoe Bay Royalty Trust is an investment trust that holds overriding royalty interests in minerals in Prudhoe Bay. Shares fell $11.52, or 13.11%, to $76.37. Aon ( AOC) gained as analysts split on their ratings for the Chicago-based insurance broker. Lehman Brothers ( LEH) downgraded Aon's stock to equal-weight from overweight, while Citigroup ( C) upgraded Aon to buy from hold. Shares gained 38 cents, or 1.19%, to $32.27. Safety Insurance Group ( SAFT) gained after the Boston-based insurer reported a 25% increase in second-quarter earnings. The company earned $29.1 million, or $1.81 a share, up from $23.2 million, or $1.46 a share a year ago. Revenue totaled $169.6 million, up from $168.1 million a year ago. Wall Street was looking for earnings of $1.32 a share. Total expenses dropped to $126.4 million, down from the year-ago figure of $134 million. The stock added $1.02, or 1.86%, to $56. First American ( FAF) acquired Greensboro, N.C.-based Offutt Systems, a provider of multiple-listing service technologies to the real estate industry, for an undisclosed sum. The Santa Ana, Calif.-based company said the deal was closed on Aug. 1. First American will continue to run Offutt operations under the direction of its current management team from the company's main office location in Greensboro, N.C. The acquisition will increase the total number of real estate professionals now served by First American MLS technology to just over 600,000, the company said. First American was off 14 cents to $38.11 recently. International Assets Holding Corp. ( IAAC) gained after the Altamonte Springs, Fla.-based asset management company said that INTL Consilium, its asset management joint venture, reached the $500 million mark of assets under management. INTL Consilium launched its first investment vehicle in July 2004 and has since launched additional funds and serves as an investment advisor to several large institutional clients. Shares gained 19 cents, or 1.19%, to $16.15.