" That’s a real number. By any reasonable measure, holding that much cash during a sustained bull run costs Berkshire shareholders meaningful upside relative to a hypothetical fully invested alternative. The trailing 12 months tell the same story. Berkshire’s Class A shares have lagged the S&P 500 by a meaningful margin over the past year as the index has continued to grind higher, and Saturday’s earnings reaction was muted despite the operating beat.

Comparing Berkshire to the S&P 500 understates what a strict value framework actually missed during this cycle. The S&P is a blended benchmark. The basket Buffett genuinely sat out was the mega-cap growth complex. The cleanest investable proxy for that basket is the Vanguard Mega Cap Growth ETF (MGK), a fund built around the largest US growth names. It captures the Magnificent Seven and the broader leadership in AI names that drove the bulk of index returns from 2020 forward.

Looking at the ten-year price-return comparison anchors the cost differently. Over the period from May 2016 through April 2026, BRK.B delivered approximately 237% in cumulative price appreciation, while MGK returned roughly 398%. That’s a CAGR gap of about 4.5 percentage points per year, compounded across a full decade."

realinvestmentadvice.com - Buffett cash hoard why billion sits on the sidelines