RE:RE:RE:RE:RE:RE:RE:MarcTo clarify,
unrealized gains or losses are typically calculated based on ((price end of period) - (price begin of period)) x #of share. End value becomes the starting value for the next period, and the "book" value is updated.
so the $50m unrealized loss is likely for 2019 only. Past years would have been calculated individually, and your $350m estimate would theoretically represent the sum of all past losses (and gains, if there had been any up years).
Definitely not pretty...
mas75