FT podcast asks if AI stock gains could be an investment bubble

In short: A Financial Times Tech Tonic live podcast episode discussed whether today’s surge in AI-related stocks could be a bubble.

What's going on

AI-related investments are now worth up to half of the total value of the S&P 500, according to the Financial Times podcast episode. The S&P 500 is a major US stock market index, which you can think of like a scoreboard that tracks 500 of the biggest publicly listed US companies.

In the episode, FT global technology correspondent Tim Bradshaw spoke with two investors, Richard Kramer, founder of Arete Research, and Ophelia Brown, founder of Blossom Capital. The discussion was recorded live at the FT Weekend Festival on 5 September 2026.

The central question was simple: is the money flowing into AI a sign of long-term growth, or is it a bubble. A bubble is when prices rise mainly because people expect they will keep rising, like bidding up the price of a collectible, rather than because the item is earning more money.

What to watch

If AI-related stocks make up such a large share of a widely followed index, big price swings can affect many retirement accounts and index funds, even for people who never buy “AI stocks” on purpose. Investors and everyday savers may want to watch company earnings, real customer adoption of AI products, and how much spending is still going into expensive computing gear needed to run modern AI systems.

Source: Financial Times