Rose Rock Midstream LP (NYSE:RRMS) is an oil and gas limited partnership formed by SemGroup. The LP provides crude oil gather, transporting, and storing services through the assets it acquires and operates. The company focuses primarily on assets in Colorado, North Dakota, Texas, Kansas, Montana, and Oklahoma. However, most of its assets are focused around or connected to the Cushing, Oklahoma crude oil marketing hub. The LP makes most of its money by charging a fixed margin or fee for services associated with the services it provides.
Because Rose Rock Midstream was created at the time of its IPO from SemGroup, it does not have any audited financial results. However, the company did report pro forma financials for the 9 months ended in September, 2011. For this period, the company reported a total revenue of $229M and a net income of $14.9M. 
The company's initial public offering of stock on the NYSE occurred on December 8, 2011. The company offered 7M shares each for $20. This was within the $19-$21 price range. The deal raised a total of $140M. The lead mangers of the deal were Barclays, Citi, and Deutsche Bank.
Rose Rock Midstream LP was formed by SemGroup, the proceeds of its IPO were given to SemGroup for its assets it transferred to the new company. However, Rose Rock continues to be dependent on SemGroup for potential future assets and acquisitions. While SemGroup owns substanital portions of Rose Rock and so the two have similar interests, SemGroup is not under any formal obligation to support Rose Rock's business operations. As a result, Rose Rock remains indirectly reliant on SemGroup.