What I was trying to get at is that there are other ways to update asset valuations besides daily (market-to-market) and once (price paid) – those are just the extreme ends of a spectrum. What makes sense really depends on the asset class and how long you're holding the positions. As for "It's the rules", I'm aware that there are strict accounting rules for companies and regular banks, but do those really apply to the central bank in the exact same way? (A central bank typically operates on a much longer time scales.)
replyIf the central bank doesn't follow rules, who would trust it? The central bank's entire purpose is to put national trust into individual banks; both assuring investments (accounts) and establishing base (prime) loan rates.
replyA central bank answers directly to the government, not the judiciary. But it still answers to power, and follows established rules.
I'm not saying it shouldn't follow rules, I said the rules might be different.
replyA balance sheet becomes pointless if some assets are valued at today's prices, while other assets are valued at their price from 100 years ago.