Merck ( MRK) has "many good quarters ahead," Jim Cramer said on CNBC's "Stop Trading!" segment Monday. The reason is Medicare Part D, the government's new prescription-drug benefit plan. "People are missing a very big story," Cramer said. " A lot of the older drugs are benefiting from people figuring out that you can get them more cheaply." Cramer said brokerage stocks could be beneficiaries of rising private equity activity on Wall Street. Driving the craze is frustration with public-market pitfalls, including exploitation by hedge funds and the inflated importance of vehicles like exchange-traded funds. "Companies are sick and tired of it, and they're going to the private equity guys and saying, 'Get me away from this stupid market,'" Cramer said. Merrill Lynch's downgrade of Halliburton ( HAL) was based on specious logic, Cramer said. He quoted the note's assertion that "investor confidence has deteriorated" and translated it as, "Lots of people are selling, get me out!" Finally, Cramer said a big purchase of August $30 calls in Kraft ( KFT) suggests the buyer must "know something." Kraft reports earnings after the bell Monday.