"First, let's understand: this market is largely driven not by stock-pickers, but by index funds," the "Mad Money" host said. "That index fund money comes in automatically, every day, over the transom. Billions of dollars placed in equities will move equities higher."
Cramer described this particular driver as "one-directional." In other words, index funds typically add money into the market rather than taking it out.
Another essential factor? Market-wide re-valuations are causing stocks like Tesla to enjoy unexpected boosts, Cramer said.
Case in point: shares of Tesla have surged since the company said it would not be able to meet its production goals for the highly anticipated Model 3 sedan.
"This market is starting to value Tesla like a tech stock. I understand it: when a tech company has a hot new product ... but can't produce it in volume this year, investors will give it a pass because they figure it'll make up that volume next year," Cramer said.
"So when Tesla can't produce enough Model 3s this year, these tech-seeking investors give it a pass — they'll sell the cars next year," he continued. "Look, I am not saying that you should give Tesla a free pass. But that's obviously what the people who trade the stock are doing given how much it's up after those miserable numbers."
Twitter has long been a part of how Cramer interacts with viewers, gets feedback and finds the hottest, most talked-about trends in the market.
"Right now, the speculators are pressing me on three major issues: marijuana, cryptocurrencies and the stock of Micron," Cramer said on Monday.
Now, Cramer might get testy on Twitter from time to time, but he respects legitimate speculation when he sees it.
But the "Mad Money" host was concerned that people buying marijuana stocks, bitcoin and its derivatives or shares of Micron didn't know they were actually speculating on these equities.
"They seem to think they're making a normal investment and I think that's a mistake," Cramer said. Find out why here.
As a biotechnology company with long-term prospects, Alkermes' treatments don't regularly make headlines.
But after years of steady growth for its leading drugs — Vivitrol, which treats opioid addiction, and Aristada, which treats schizophrenia — 2018 will be a year of milestones, Alkermes CEO Richard Pops told CNBC on Monday from the J.P. Morgan Healthcare Conference.
"I think the best days of Vivitrol are still ahead of it," Pops told Cramer. "It's building into becoming one of the more important medicines for the treatment of this condition."
"We want to address the top 10 cancers, not just colon cancer," Conroy said, also speaking from J.P. Morgan's Healthcare Conference. "[Cologuard] was really a breakthrough technology that powers this pretty incredible test, and now we're working on a test for lung cancer and a test for liver cancer."
Conroy stressed the importance of Exact Sciences' years-long partnership with the Mayo Clinic to developing new tests like Cologuard, which is approaching its millionth screening.
"Just recently, we were able to meet one of our customers from Georgia," Conroy told Cramer. "She was diagnosed with Stage 1 colon cancer. She had surgery, and two weeks later, she was at work. No chemotherapy, no radiation therapy. She was healthy and she felt healthy when she got the Cologuard test. Detecting cancer early is key and that's why we're partnering with the Mayo Clinic."
In Cramer's lightning round, he rattled off his take on some callers' favorite stocks:
Seattle Genetics, Inc.: "You know, Seattle Genetics is trading with all the biotechs and it shouldn't. It's got a lot of stuff in the pipeline, but let's accept the fact that the biotechs … right now are in some sort of bearish phase. These always end."
AbbVie Inc.: "AbbVie is just fabulous. I think it can still go higher even though it's been a monster."