Rose Rock Midstream GP, LLC and SemGroup Corporation announced that Paul F. Largess intended to retire as vice president, chief accounting officer, and controller of both company's on March 15, 2016. On February 23, 2016, the Board of Directors of the General Partner appointed Thomas D. Sell, age 50, as vice president, chief accounting officer, and controller of the General Partner effective March 15, 2016. The Board of Directors of SemGroup Corporation also appointed Mr. Sell to serve as vice president, chief accounting officer, and controller of SemGroup effective March 15, 2016.

From 1996 to 2016, Mr. Sell served in a variety of finance, accounting, and financial reporting roles for The Williams Companies Inc. Most recently, he served as staff vice president, enterprise accounting for Williams since 2013. as vice president of finance & accounting, midstream from 2008 to 2013, and as assistant controller from 2005 to 2008.