Berkshire Hathaway said Saturday it lost $12.8 billion, or $8,824 per Class A share, for the quarter. That's significantly wider than the loss of $2.8 billion, or $1,907 per Class A share, it reported a year ago. But most of those investment losses went unrealized because Berkshire didn't actually sell most of its shares, and its largest holding was its huge stake in Apple. Accounting rules require the company to include in its earnings the value of its investments, which it valued at $341.1 billion at the end of the quarter. Last quarter, the company said its stock portfolio...