For some amount of time, sure. But at some point you have to pay off the loan, presumably by selling the collateral, at which point your taxes still come due an

For some amount of time, sure. But at some point you have to pay off the loan, presumably by selling the collateral, at which point your taxes still come due and you've also paid a bunch of interest. This only makes sense if you believe the stock will increase in value enough to exceed the interest paid. If you're actually donating the stock (or the full proceeds from the sale), I'm not sure what the tax implications are anyway. You get a write off for the value of the donation, which will by necessity exceed the value being taxed. I think you actually come out ahead. But I'm no tax expert.