Not exactly a falling knife, but one that drifts around between about $55 - $65 fairly regularly for the last year or so, and between $55 and about $72 in the prior couple of years. So it is very close to the lowest it's been.

Oil prices are down a bit, to $73 a barrel, close to the bottom of their range this year of $68 to $91, so that's probably the reason.

Small dividend, but using its cash flow to reduce long-term debt, $3b this year by the 3rd quarter, out of a total of $18b now. Debt was $35b 3 years ago.

In the last couple of years, Buffet's buys typically occur when the shares dip under $60. The market has become somewhat indifferent to announcements of Berkshire buying more, so I don't expect that would be a catalyst.

But one thing that would light a fire under the price is a takeover offer. Berkshire owned 255m shares on June 30, along with options to buy 84m more, which would give Berkshire 35.5% of the company. Buffett has said he has no interest in taking the company private, but you never know when someone might change their minds, especially if they were sitting on an uncomfortable pile of cash...