While the artificial intelligence boom brought stocks to record highs in the first half of the year, concern has mounted that valuations are stretched. Strategists polled by CNBC Pro say that market gains in the rest of 2024 may be harder to come by , forecasting that the S & P 500 will add just 1% based on median price targets. Some market pundits have noted anxiety over valuations, saying price-earnings ratios and other yardsticks may be getting ahead of themselves. They also highlight signs of exhaustion in some formerly high-flying stocks. That forecast comes as Nvidia entered a correction earlier this week, adding to worries dating from late last year that too few stocks have participated in the latest up-move. Against this backdrop, CNBC Pro screened for some of the most expensive stocks on Wall Street, using the following criteria as a filter: Current price-earnings ratio is more than 50% higher than the stock’s 5-year average price-earnings ratio Each stock’s current forward price-earnings ratio is above the S & P 500’s forward price-earnings ratio of 21 Readers can customize their screen using the CNBC Pro Stock Screener tool here . Data in the table below is current as of Tuesday. Artificial Intelligence plays Top AI plays were among the list of expensive stocks in the S & P 500, including Broadcom , Lam Research , Intel and Super Micro Computer . All of the AI plays on the list have trailing 12-month price-earnings ratios more than double their five-year average. Beyond Nvidia, shares of Super Micro Computer and Broadcom have been two of the biggest beneficiaries of the AI boom, sporting gains of more than 188% and 42%, respectively. Each stock’s price-earnings ratio equates to a roughly 60% to 66% premium over the historical average. SMCI YTD mountain Super Micro Computer stock. Broadcom’s fiscal second-quarter results reported earlier this month surpassed Wall Street estimates for earnings and revenue, and it declared a 10-for-1 stock split. Bank of America posited that the company could soon join the likes of Nvidia with a multitrillion-dollar valuation. Super Micro Computer, meanwhile, has continued to ride the AI wave despite some weakness last month after third-quarter revenue missed analyst expectations. The stock found more upside last week after Elon Musk said that both Super Micro and Dell would provide servers to power xAI’s forthcoming supercomputer. Wariness surrounding how much higher stocks at the forefront of the AI boom can rise has grown as the stocks have become more detached from the rest of the market. At the same time, investors are beginning to wonder if the robust spending these companies are deploying on AI signals that applications will soon deliver higher profits. AVGO YTD mountain Broadcom stock. “Given the focus and architecture of generative AI technology today… truly transformative changes won’t happen quickly and few — if any — will likely occur within the next 10 years,” Massachusetts Institute of Technology professor Daron Acemoglu was quoted telling Goldman Sachs global macro analysts in a June 25 note. Eli Lilly Eli Lilly also turned up as expensive, after shares of the GLP-1 weight loss drugmaker have soared more than 54% in 2024. The stock’s trailing 12-month price-earnings ratio is also more than double its five-year average, at a 63% premium. The company continues to benefit from sky-high demand for GLP-1 drugs. Eli Lilly also saw an independent board of advisors to the U.S. Food and Drug Administration recommend its Alzheimer’s treatment donanemab , opening the door for its approval. If given the green light, the drug would be just the second treatment of its kind in the U.S., alongside Biogen’s Leqembi.