Peter Thiel @peterthiel: Every time a company had a big up round led by a smart investor, it's always a good idea to do your pro rata. For flat rounds and down rounds, it was almost always a bad idea. The steeper the up round, the cheaper it was. The biggest mess of the last decade was not doing our pro rata, e.g. Series B at @facebook. Every liquid token book runs the same two errors: trimming the winner because it's "too big a position now," and averaging down the loser because it's "cheap."That's the Facebook Series B mistake — except repeated weekly, with better liquidity and worse excuses.