I'm planning to buy a house, and the downpayment would come from the funds I'd get from selling some stock. Can I apply for the mortgage pre-approval and show the bank my stocks instead of cash? Or will they need to see cash, and if so, would they require that cash to be available on my account for some period of time?
Yes, you can. They'll require that the funds be in your account for closing, obviously, but you can show them investment accounts that you'll be using for the downpayment. (source: I've done it)