Everywhere Jim Cramer goes, investors ask him if it is too late to participate in the stock market's incredible rally.
"If you want to understand how this market has been able to run so much since the election … you have to stop thinking of the stock market as some kind of unified whole, and start viewing it as a market of stocks," the "Mad Money" host said.
The stocks leading the charge higher are a lot less vulnerable than many investors think, Cramer said. In fact, stocks that have led the Dow Jones industrial average to the brink of 20,000 are entirely justified to be at these levels.
More importantly, Cramer thinks the run could be sustainable because of overhead resistance. This refers to the amount of stock for sale. One thing Cramer noticed is that a large portion of the gains in the Dow are from the stocks that up more than 10 percent since the election, and don't have a lot of overhead supply.