Second thought: The numbers don't seem to check out: 129t are 4,147,456.307 troy ounces (1 troy ounce = 31.1034768 g). The total gains of 15e9 USD would thus correspond to gains of $3,616.68 per troy ounce, which seems excessively high, given that today's gold price is at ~$4,712. Even if they sold everything at the current all-time high of $5,589.38 on January 28 (and that's a big if), they would have had to buy for not more than $1,972.70, a price we last had in fall 2023.
They must have had an exceptional crystal ball!
And how does a 10% market shift lead to gaining $15b, roughly the value of 100 tons of gold, from the sale and re-purchase of 129 tons of gold?
This math ain't mathing.
The mining.com quote is classic weasel phrasing, seemingly meaningful yet disturbingly ambiguous:
Due to rising gold prices, the move helped the bank to generate a capital gain of 13 billion euros ($15 billion), bringing it to a net profit of 8.1 billion euros for the 2025 financial year after a net loss of 7.7 billion euros in 2024.
Just as, say, one guy helped four others push a car back up on the road.
We've been given, accurately or not .. likely true, figures on how the bank did over a period, we've also been told the gold movements helped with that ... so they almost certainly kicked in at least $1.
Keep in mind that 129 tons of gold is worth just a bit more than $15b, so small market fluctuations on the scale of 10% isn't enough by itself.
They then sold the 129 tons gold in the US vaults for $16 billion. That gold was originally purchased I'm guessing many decades ago for $1 billion. The have a book profit of $15 billion and still have 129 tons of gold.
They captured some of the appreciation in gold value as a realised profit on their books.
Their balance sheet did not change, just their income statement