The known portfolio isn't toxic with more time. It's just Treasury bonds and MBS. In fact they are rising in price because of SVB. However, the suspected problem is the unpublicized part of the portfolio. Some here say there are funny, poorly collateralized loans in there to the same people who made deposits there. It might turn out to be out-and-out fraud that looks like clever financial engineering.
Thats not what parent is saying. They are saying todays value of the known portfolio is not what is on the books due to interest and risk discounting the future value at which the bonds mature.
Either you sell everything now at the discounted value, leading to loss in deposits. Or you wait 10 years and pay everyone back their deposit then. Given current inflation a dollar now is only worth 50 cent in 10 years.
Sure, the "known" portion may not be getting more toxic, but an acquirer has to take the whole thing. The "known" and the "unknown" part you're talking about. As it goes on, people are going to increasingly wonder why no one has stepped in to buy what would otherwise be a pretty lucrative business
It's because there's a lot more bad assets there than people know or acknowledge, and most of the deposits (and therefore customers) are gone. And as time ticks on, that continues to get worse, even if it's just a perception of it getting worse that perception becomes reality
