Vanguard S&P 500 ETF valuation hits 42.8 CAPE, safety questioned

The Vanguard S&P 500 ETF (VOO) now trades at a forward price‑to‑earnings ratio of about 21 and a Shiller CAPE of 42.84, levels that match the peak of the 1999 tech bubble and far exceed historic averages【2】. This raises questions about the fund’s safety as AI‑driven valuations push the broader index toward historically expensive territory.

Valuation pressure on the S&P 500

Bloomberg research notes that AI‑related stocks now comprise roughly 53% of the S&P 500 by weight, inflating earnings growth but also pushing valuations higher【1】. The forward P/E of 21 for VOO is “well above its long‑term average,” though it sits below the range seen over the past five years【2】. More striking is the Shiller CAPE of 42.84, essentially identical to the 44.19 level recorded at the height of the 1999 dot‑com bubble and far above levels during the Great Depression, the 2008 financial crisis, and other market cycles【2】. Such a gap suggests that price appreciation may be outpacing underlying earnings, a classic red flag for long‑term investors.

Alternatives to blunt AI‑centric risk

The same Bloomberg analysis proposes adding exposure to energy stocks and U.S. Treasury bonds to temper volatility without sacrificing much of the S&P 500’s return profile【1】. The Vanguard Energy ETF (VDE) has delivered an 8.19% average annual return since 2004 and a striking 21.1% annualized return over the past five years, outpacing the index【1】. Meanwhile, the Vanguard Total Bond Market ETF (BND) offers a low‑cost, diversified bond basket that returned 3.95% annualized over the last three years, providing a steadier footing during equity downturns【1】. Both funds carry ultra‑low expense ratios (0.09% for VDE, 0.03% for BND) and could serve as defensive complements to a VOO‑centric portfolio.

What to watch

• CPI and earnings releases in the next two months – higher inflation or weaker earnings could push the forward P/E and CAPE even higher.
• AI capex trends – a slowdown in AI spending would test whether current earnings growth can sustain elevated valuations.
• Bond‑market yields – a rise in Treasury yields would affect BND’s relative attractiveness and could shift the risk‑return balance between equities and bonds.

The juxtaposition of VOO’s strong historical performance with valuation metrics at bubble‑level highs underscores a core dilemma: while the fund remains a “short‑term buy” on earnings momentum, its long‑term safety is uncertain unless valuations retreat or diversification offsets AI‑driven concentration. Investors must weigh the trade‑off between staying fully exposed to the S&P 500 and adding energy or bond ETFs to hedge against a potential AI‑centric market correction.