Bloomberg’s Carol Massar Says 10 AI Stocks Drove More Than Half of the S&P 500’s $32 Trillion Gain Since ChatGPT. Our Count: 56%, and One of the 10 Is a Drugmaker

Bloomberg Businessweek opened its Nov. 9 show with the S&P 500’s post-election drop. Co-host Carol Massar said the possibility that newly elected Democrats would slow data center development “was enough to send stocks reeling.” Then she read out a number from a Bloomberg News analysis to explain why: as of Nov. 3, “nearly $32 trillion in market value had been added to the S&P 500 index since OpenAI released ChatGPT.”

That is a big claim about how much one theme now drives the U.S. stock market. We rebuilt the count ourselves, company by company, to see if it holds.

We Redid the Count

For each of the 496 companies in the S&P 500 today, we multiplied its share count from its SEC filings by its closing price on Nov. 30, 2022, the day ChatGPT came out, and again on Nov. 3, 2026. Their combined value rose from $36.2 trillion to $68.7 trillion, a gain of about $32.5 trillion. That is close to Massar’s “nearly $32 trillion.” (Our count uses today’s members; companies spun off or listed since 2022 count from zero.)

The 10 biggest gains added up to $18.3 trillion, or 56.5% of the total. Massar’s “more than half” checks out. Nvidia NVDA alone added $4.6 trillion, going from about $416 billion to nearly $5.0 trillion. That single company accounts for 14% of the index’s gain.

One of the 10 Isn’t an AI Stock

Massar said all 10 were linked to artificial intelligence. Nine of the top 10 in our count are names tied to the AI trade: Nvidia, Apple, Alphabet, Microsoft, Amazon, Broadcom, Meta, Tesla and memory maker Micron MU, whose value rose from about $63 billion to $967 billion. No. 8 is Eli Lilly LLY, the drugmaker best known these days for its weight-loss drugs, which added about $1.0 trillion.

Swap Lilly for the next AI name on the list, Advanced Micro Devices AMD at $0.7 trillion, and the AI 10 still account for 55.6% of the gain. Either way, the claim holds. The other 486 companies added $14.1 trillion together, and 126 of them are worth less than they were when ChatGPT launched.

The S&P 500 since ChatGPT, Nov. 30, 2022 to Nov. 3, 2026

The Biggest Stocks Pulled Far Ahead

The 10 largest companies now make up 39.4% of the index’s value by our count, up from 26.9% for the 10 largest when ChatGPT came out. The gap shows up in returns, too. Including dividends, the S&P 500 SPY returned 94.9% from Nov. 30, 2022 to Nov. 3, 2026. An equal-weighted version RSP, which gives every company the same weight, returned 57.4%. That is a 37.4-point lead for the biggest stocks. It fits with Schwab’s finding that fewer than half the index’s stocks were above their 200-day averages this fall.

To put the lead in context, we measured it over every stretch of the same length, 1,434 days, since the equal-weight fund launched in 2003. The current gap is wider than in 98% of them. Before 2023, the widest was 32.1 points, for the stretch ending in September 2020. Every wider reading came this year, peaking at 54.9 points on Oct. 7, 2026.

It has run the other way before. For the stretch ending in early 2013, which started near the bottom of the financial crisis, the equal-weighted index led by about 56 points as smaller and beaten-down stocks rebounded.

What to Watch

Massar also cited a figure on pension funds’ exposure to tech. We could not trace its source, so we left it out. Frier’s point on the show was that there is no easy way out of the trade: “There really isn’t a way to do a fully AI-free portfolio,” she said, pointing to energy, credit and Washington. Some investors, such as Neuberger Berman’s Joe Amato, have argued it’s time to diversify.

The next big test is Nvidia’s quarterly report, which Alpha Vantage’s earnings calendar lists for Nov. 17 after the close. One company drove about a seventh of the index’s gain over four years, so its results move far more than one stock. Comparisons with 2000 come up often; Josh Brown has argued Nvidia trades nowhere near Cisco’s bubble valuation. The number to watch is the gap between the S&P 500 and its equal-weighted twin. If it keeps narrowing from October’s peak, the rest of the market is catching up, or the leaders are falling.