"This market's rotating into what's been left behind of late. That's healthy. Hey, you know what? It's health care. That's right, health care's catching up. How can you spot these rotations? It's simple. Let me give you my No. 1 rule of thumb for spotting rotations," the "Mad Money" host said. "First, you look up what stocks are rallying the most. You can look at percentage gains or big [basis] point gains. Then you see if there's any news or research behind the particular move that you're seeing. If there's nothing to it, if there's no obvious reason, then you know what you're witnessing? The beginning of a rotation."
Cramer pointed to the stock of Johnson & Johnson. Shares of the medical goods giant had been steady since their last real rally in February, but recently, they've been jumping higher.
"That's perfect. That's the first lead," Cramer said. "Big-time money managers don't want to buy stocks that have run. They want to buy stocks that are about to run."
Now, despite the lack of news fueling Johnson & Johnson's run, Cramer expects analysts covering the stock to step out tomorrow and reiterate their "buy" recommendations.
Analysts covering steady stocks like this one often wait for big moves to voice why they like or dislike their stocks even without clear catalysts, the "Mad Money" host explained.
And it's not just Johnson & Johnson. Cramer noticed the same thing with the stocks of Merck and Pfizer, two other big-name pharmaceuticals.
"But what, you're saying, is worth squawking about if there's really no reason for the J&J move? If you're saying that to yourself, you're a big silly, because something can always be ginned up," Cramer said.
For example, Johnson & Johnson analysts can point to the company's massive overseas sales, particularly in Europe, as cause for the stock's rise. They can cite currency fluctuations in their upgrades, Cramer said.
But the most important thing for investors to understand about rotations is that bulls in bears' clothing are always lurking, searching for areas of value they can recommend despite the news cycle.
"It doesn't take much to get a short-term rotation going, even if many of these moves might not have long-term staying power," Cramer said. "I'm not saying to relax and enjoy the ride, [but] the opposite — that's just complacency. I am staying to observe and understand, and then at least you can make sense of the action."