Berkshire 13F shock: its own stock moved just 0.4%!

A big filing landed, and the holdings data behind it is missing

Berkshire Hathaway filed its 13F for the second quarter of 2026. A 13F is a form that large investors in the United States must send to the regulator once a quarter. It lists the American shares they held on the last day of that quarter. Think of it as a group photo of the portfolio, taken weeks before anyone outside the firm gets to see it.

One honest warning before we go on. The detailed holdings behind this filing are not available for this note, so the exact position sizes are absent here. What we still have is the share price of Berkshire Hathaway itself around the day the form reached the public. That is a smaller story than the headlines, and it is one you can check yourself.

What you are reading is already old news

Here is the catch with every 13F. The holdings describe the last day of the quarter, 30 June 2026 in this case, while the form only reached the public in the middle of August. Weeks of trading sit in that gap. Positions can grow, shrink or disappear in that time with no public notice at all.

That gap matters more than most people think. Someone copying a filing is copying a decision made at a price that is already gone. The form also leaves things out, such as bets against stocks, most option detail and holdings listed outside the United States. So read it as a clue about how a large investor thinks, not as a to-do list.

The price data in this note runs through 26 August 2026, the last date available to us, so everything below describes that window and nothing after it.

The market shrugged at the news

Now the price. In the trading days from the filing becoming public, Berkshire Hathaway shares moved 0.4% against the market, meaning after stripping out how the wider market did over the same days. Watch the wording: this happened in the same window as the news, which is not the same thing as the news causing it. A form that tells you about June is rarely much of a surprise in August.

One more honest number. Only 1 stock is measured here, Berkshire Hathaway itself, because the holdings list was not available. So this is not a read on any of the individual companies named in the press coverage. It is one line, for the filer, over a short window.