Cramer says the rally in infrastructure stocks shows the newfound power of retail investors
CNBC's Jim Cramer said the rally in infrastructure-related stocks Monday demonstrates the growing influence of retail investors on Wall Street.

The "Mad Money" host expressed surprise that companies such as steelmaker Nucor and construction materials supplier Martin Marietta moved solidly higher during Monday's session, which was the first since the House of Representatives passed a more than $1 trillion infrastructure bill late Friday.

"Historically, you had to buy before something good happens, and then sell into the news. The smart money always loaded up and crushed bids when stories broke, often leading to big losses for anyone who bought the news," Cramer said. "Not this market, though. The new pattern is insane if you've got experience, but it's making fortunes for newcomers."

Cramer pointed to Nucor, in particular, to make his case. While he noted he's maintained an optimistic outlook on Nucor, he said there have been others on Wall Street who believed its stock had fully priced in most of the potential benefit from an infrastructure deal.

"In the old days, once we found out Congress had finally passed the infrastructure bill, you might've seen Nucor's stock open up a point or two before the heat-seeking sellers came in and lit up the buyers, taking furious profits. In the end, they might've blasted this thing back down to where it was trading a week ago," Cramer said.

However, Cramer said the current market is no longer dominated by large institutional money managers.

"Individual investors have a lot of power," Cramer said, noting Nucor shares finished up 3.6% Monday. The stock is up 18.65% in the past month.

"See, Nucor was too obvious for the pros. But regular individual investors no doubt wanted to be sure the bill would actually pass before they pulled the trigger. Then they started buying hand over fist and I don't think they're finished," Cramer said.

"The professionals keep being wrong because these new buyers aren't used to the cynical trading ways of Wall Street," he added. "They hear good news; they buy good news. It's a new world, more straightforward, less pessimistic, and you ignore this optimism at your own peril."

Sign up here for the new CNBC Investing Club newsletter to follow Jim Cramer's every move in the market, delivered directly in your inbox.