Normally you get up to 95% with seller carryback. 100% financing is attainable if you have a stock. This is how it works. The lender can lend up to 90% depending on what type of stock you have.
You use that for down payment, lenders fee and closing cost
If 90% of your stock can cover your downpayment, fees and closing cost. Then you get 100% financing
I concur with donedeals—the highest CLTV you can achieve with a seller second is 95 (with a 75% lender 1st combined with a 20% seller 2nd).
You could either apply for a stock portfolio loan or a unsecured LOC to make up the difference (assuming that you either have the stock value or qualify for the unsecured LOC).