By David Fischer, David Blair, Charles Hwang and Madeline Obler (July 30, 2018, 3:41 PM EDT) -- In last week's Altera Corp. & Subsidiaries v. Commissioner of Internal Revenue[1] decision, the U.S. Court of Appeals for the Ninth Circuit reversed the U.S. Tax Court and found that a regulation requiring cost sharing of stock-based compensation was valid under the Administrative Procedure Act. The 2015 decision in Altera Corp. v. Commissioner of Internal Revenue[2] was one of the most significant Tax Court cases in recent years both for its transfer pricing holding and, perhaps more importantly, because it provided a landmark application of the APA to tax regulations. The reversal has important implications for cost sharing, specifically, for the use of the APA, and for transfer pricing more generally....