Equities may be used as collateral for a loan. In the US this is sometimes referred to as Securities Based Lending.
Example #1 - Merrill: https://www.ml.com/solutions/structured-lending.html
Example #2 - Wells Fargo: https://www.wellsfargoadvisors.com/why-wells-fargo/products-services/lending/securities-based.htm
If you are buying a house, keep in mind that typically that subject property would be the collateral, not your other assets. You could if you want get a lower rate through balance transfer pricing where you move your assets to the lender's broker (e.g., Merrill for Bank of America, Wells Fargo Advisors for Wells Fargo) to get 25-75 bps off the rate. Your stocks could also be used as assets for qualifying purposes for the home loan (when requiring a certain amount of cash to close or a number of months of reserves). This is assuming we're talking about residential home loans here. This could be combined: move assets to get the better pricing for the home loan, then use the assets for Securities Based Lending to help fund your EB-5 strategy.