I don't forget the facts. The SEC told Buffett to mark the ibm, his position was, it was short term weakness, he wasn't selling, therefore no reason to mark the position, since it was not material.

Enjoy your workout. I don't know why Berkshire's IBM would have ever *not* been marked to market but maybe you are referring to the SEC perhaps wanting the unrealized loss to pass through the income statement, since at that time unrealized stock portfolio fluctuations didn't pass through the income statement like they do today.

I do know that the SEC has asked Berkshire at least once, maybe more, about their equity method value of KHC being above the market price of KHC stock. Berkshire resisted the write-down at the time.

There was also another SEC letter asking for details about Berkshire's investment in the bonds of Texas Competitive Electricity or whatever those TXU leveraged buyout bonds were called. I forget the details but that was a bond investment and Berkshire had taken an 'other than temporary impairment' and the SEC wanted to know what the story was.

By the way, Berkshire just published some more SEC letters this week. This time some SEC functionary wants more detail on Berkshire's proxy statement.

link to recent SEC letter to Berkshire, opens a PDF:
U.S. Securities and Exchange Commission: Filing