Stock Investing with Quick Withdrawal for Off-Market Purchases

[James Free]

Outside of real-estate, most of my money is parked in Vanguard funds. Recently, I purchased a property using some of the Vanguard money as a down payment, and discovered that withdrawing the funds took over a week before money was available in my checking account! I have reason to believe that it will be faster next time (no "account verification" steps), but it still seems like several days' delay is the norm for accessing your money when it's invested with Vanguard.

I don't want to keep more than a couple of months' expenses in a mere savings account earning nothing, but I also want my more significant capital to be available for quick-closing off-market deals. So I'm asking - where do other investors in my situation park their capital when it's not in a property? Has anyone found an investment platform that allows quicker access to your money than Vanguard?