Shares in Alphabet, the tech giant that owns Google, rose almost $10 to an all-time closing high of $1,440.03, pulling within 1% of reaching $1 trillion of market capitalization.
"Now, I don't like this move. It's based on nothing fundamental, just the momentum that we see in so many tech names," the "Mad Money" host said.
Alphabet was worth about $992.7 billion as of Monday's close, a couple of slots away from being the most valuable company on Wall Street.
Alphabet stock climbed more than 28% in 2019, shy of the 35% gain that the Nasdaq Composite it trades on made in the year. The stock has had just two down days thus far in 2020 and has advanced a total of 7.64% since the start of the year, which beats the tech-heavy Nasdaq's nearly 3.4% gain.
Three other tech behemoths have crossed the $1 trillion mark, including Microsoft, Apple and Amazon, though the latter now holds a market cap of $937.7 billion. Apple captures nearly $1.4 trillion of market value, while Microsoft holds $1.2 trillion, according to FactSet.
Facebook, the runner-up to all of the aforementioned companies, is worth almost $633 billion. No other company is valued above $500 billion by the market.
While these companies all hold high valuations of varying levels, they all share a common denominator in Cramer's eyes: the fundamentals. Cramer worries they'll have a tough time justifying their recent gains when they report quarterly performances in coming weeks.
He fears their stocks could recede if they do not report substantially higher-than-expected numbers.
"We're witnessing the same thing in the two other stocks in the trillion-dollar club, and that's Microsoft and Apple, which means their stocks may not be able to withstand any earnings results short of a super beat, not just 'better than expected' by a couple of pennies. I don't know if that's even possible," Cramer said. "Hey, by the way, Facebook's in the same boat."
Disclosure: Cramer's charitable trust owns shares of Alphabet, Facebook, Microsoft and Amazon.