Exactly. I got this pointed out by one of the old school finance guys I've followed for years on Twitter/bsky; if you're a market participant of that size, other participants should expect to know who you are. If only because someone buying a billion dollars of bonds a week is useful to know if you want to unload some bonds.

USDC by contrast are open in their holdings, through Blackrock.

Large invisible "dark matter" financial holdings are the sort of thing that blow up badly during a financial crisis.