I'm not an expert. But it appears to be an accounting designation that shows up in filings, so it's not purely internal. You are correct that they are not part

I'm not an expert. But it appears to be an accounting designation that shows up in filings, so it's not purely internal. You are correct that they are not part of the bond terms, which I was unclear on before. "HTM assets are not marked to market... they remain glued to balance sheets at amortised cost regardless. By contrast, AFS assets are marked-to-market... Sell even a single bond out of an HTM portfolio, however, and the entire portfolio would need to be re-marked accordingly." There's a bit more detail here, but it doesn't get into the re-marking aspect. https://www.investopedia.com/terms/h/held-to-maturity-security.asp https://www.investopedia.com/terms/h/held-to-maturity-securi...