2022 has marked the end of an era of cheap money, and that’s bad news for companies with a “growth at all costs” approach, said David Trainer, CEO of investment research firm New Constructs. In the year ahead, investors will need to exercise due diligence in distinguishing between good and bad firms, he told CNBC Pro. That’s because the U.S. Federal Reserve’s interest rate hikes in 2022 have “ended the era of super easy money,” and exposed many companies with bad business models. He calls those companies “zombie stocks” with heavy cash burn. He said he’s seeing stocks “get hit hard” after their bad business models are exposed. “Too much capital has been allocated to bad investments, bad people and bad ideas, e.g. FTX, Zombie Stocks, Meme Stocks, ESG,” Trainer said. He was referring to the massive fallout after cryptocurrency exchange FTX filed for bankruptcy in the United States, amid investigations for losing and misspending billions of dollars in user deposits. “Until these misallocations are rectified, our economy and market will struggle to grow at normal rates,” he said. He urged investors to do their homework. “Do the companies in your portfolio have the balance sheet and cash flows to withstand a slowdown in economic activity, or have they taken a growth at all costs approach that is unsustainable as the era of free money comes to an end?” “If the latter, investors could be holding stocks at high risk of falling (even more than they may have already),” Trainer added. ‘Zombie’ stocks to avoid Trainer, a former Wall Street analyst who has been bearish on tech stocks, compiled a list of “zombie” companies which risk of running out of cash. Zombie companies refer to those that have been on the market for more than 10 years and earn enough to operate, but not to pay the interest on their debt. Trainer told CNBC Pro that those zombie stocks, which could “go to zero,” include online used car retailer Carvana , online home goods retailer Wayfair , payments company Affirm and cloud services company RingCentral . Some of those stocks have lost a vast majority of their value in 2022. Carvana plunged around 98% for the year, while Wayfair tumbled about 83%. Affirm lost nearly 90% and RingCentral was down around 82%. What to buy instead Growth stocks such as tech firms have benefited from the an era of low rates. But investors should now be selective when looking at the sector, Trainer said. Trainer told CNBC Pro that the best tech stocks to buy are those with strong cash flows and with valuations that underestimate the firm’s ability to generate cash in the future. His favorite tech stocks include Qualcomm , Alphabet , Cisco and Oracle .