The preponderance of evidence says that when they're put on sale, you have to buy them. That's what comes to mind when I think of FedEx ( FDX), Caterpillar ( CAT), Deere ( DE) and Oracle ( ORCL), all of which have been hammered terribly in the last 24 hours. Now, the evidence behind the selloff does not indicate it is a wise decision to buy. FedEx blew it again. It has an expensive route system, one that can't be supported by the high-end fast delivery of packages -- at least right now. Caterpillar blew it again. It makes gigantic engines and equipment that can't be supported by commercial real estate, trucking, oil drilling or infrastructure spend -- at least right now. Deere blew it again. Turns out that, without rising prices in corn, the company can't sell enough equipment -- at least right now. Oracle blew it again. It had a difficult hardware transition; it added 4,000 new salespeople and didn't get much out of them, and it didn't have luck closing a lot of big deals -- at least right now. So aren't all of these sales? Yes, but they have already been put on sale by a market that instantly over-punishes but does not instantly over-reward. That's the issue that confronts bargain hunters at this very moment. This article originally appeared on March 21, 2013, on RealMoney. To read more content like this + see inside Jim Cramer's $3 Million portfolio for FREE Click Here NOW. Let me walk you through my thinking. First, FedEx. We don't know if this company's problems are cyclical or secular. It looks as though FedEx is offering a very expensive product that people don't really need right now -- the fast-shipping option. But if things get better globally, won't people pay up for the service as they used to do? I think they will. In the meantime, they are taking down costs and bringing in new planes to make service cheaper. How do you know it won't click? More important, think back to what happened with FedEx back in September and October of last year. The company first guided down then, citing pretty much the exact same problems that hurt it Wednesday. That's right, the exact same problems. That news sent the stock from the low $90s down to the mid-$80s in a similar bloodbath to Wednesday's percentage decline.