The South Korean conglomerate SK Holdings will acquire Ampac Fine Chemicals as part of its plan to become a top-tier pharmaceutical contract development and manufacturing firm. Owned by the private equity firm H.I.G. Capital, Ampac operates plants in California, Texas, and Virginia and is one of the largest U.S. producers of pharmaceutical chemicals. Its Virginia facility was once owned by the drugmaker Boehringer Ingelheim. SK has drug chemical operations in South Korea and last year acquired a Bristol-Myers Squibb plant in Ireland.