DOW JONES NEWSWIRES The Pension Benefit Guaranty Corp. said Gerdau S.A. (GGB, GGBR4.BR) agreed to pay an additional $18.6 million toward two pension plans covering more than 780 of the steel producer's workers and retirees. The company shutdown its Sand Springs, Okla., steel mill in October 2009, affecting the Retirement Plan for Employees of Sheffield Steel Corp. and the Sheffield Steel Corp. Pension Agreement Plan. Gerdau will make the payment, which exceeds its required plan contributions, over the next three years. The PBGC is a federal corporation created in 1974 to protect the pensions of nearly 44 million U.S. workers and retirees. Gerdau, Latin America's biggest steelmaker, reported last week its second-quarter profit plunged 41% due to higher raw materials costs. Its American depositary shares were trading 6.4% higher at $7.54, rising along with the broader market. -By Melodie Warner, Dow Jones Newswires; 212-416-2283; melodie.warner@dowjones.com