NEW YORK, Aug 20 : S&P 500 companies are winding up a banner quarterly earnings season, fueled in large part by surging profits at AI-related companies.The S&P 500 is on track for a 52 per cent surge in aggregate second-quarter earnings from the year before, helped by a 74 per cent profit jump in the technology sector. The figures include big mark-to-market boosts at Alphabet and Amazon, both of which recognized large gains in the period on investments in AI highfliers such as Anthropic.Excluding those gains, the latest estimate for S&P 500 second-quarter profit growth would be 33 per cent, according to Tajinder Dhillon, head of earnings research at LSEG. That is still the strongest quarter since 2021, in the wake of the pandemic's start, but the gap is worth considering because many investors view mark-to-market profit gains with caution as they can accentuate the impact of market swings on a company's performance. "Mark-to-market gains can turn into losses just as fast," Savita Subramanian, equity and quant strategist at BofA Securities, wrote in a recent client note. "We are not arguing mark-to-market gains are bad, though we remain cautious that increasing earnings dependence on (largely) uncontrollable factors reduces visibility."