Defense behemoth Lockheed Martin is considering the sale of $600 million in alternative assets in order to reduce its exposure to private equity funds. The assets are reportedly housed at Lockheed Martin Investment Management Co., the unit responsible for managing the company’s retirement plans, according to a Pensions and Investments article citing unidentified individuals familiar with the matter.  Lockheed is the world’s largest defense contractor and maker of the F-35 Joint Strike Fighter. It recently acquired helicopter maker Sikorsky from United Technologies in a $9 billion deal expected to close on Friday. However, not everyone is impressed; Standard & Poors downgraded the...