Best OTC desk for large SOL to ETH swap?

Trying to swap around $500k SOL into ETH, but all the big exchanges are either painfully slow or require ridiculous amounts of KYC that make moving such a large sum nearly impossible. Does anyone know trusted OTC desks or platforms that can handle high-volume trades safely and reliably?

I’m mainly worried about slippage, fees, and keeping funds secure, because I really don’t want to risk half a million disappearing.

Any real advice or experiences from people who’ve actually done this would be incredible.