Berkshire Hathaway (BRK.A) Up 51% in After Hours Trading

Would it be just one rogue order filled? Not sure how after-hours tracking works, but I assume that it won't have a very deep order book, so it would be relatively easy to manipulate it. Given that BRK.A has the highest share price among any stocks, that order book would be even smaller.

It was 4 shares: https://www.nasdaq.com/market-activity/stocks/brk.a/after-ho...

Likely one person that placed a market order

I don't think you can place market orders after hours.

It could have been a deliberate limit order to avoid a margin call by raising the mark-to-market value of an account.

That sounds like an expensive mistake -- BRK.B doesn't show anywhere near the same price movements.

One does not simply place a market order during after hours trading...

https://www.google.com/finance/quote/BRK.A:NYSE shows a volume of 1 single share at that time.

We assume that hedges / banks are moving their money into higher quality assets before the new margin requirements take effect on October 29th.

How so?

Another one, not quite 51% this time.