I'm actually rather surprised long doubles for individual stocks do not exist (at least, not as far as I can tell). Given this environment, I would think being able to long double specific stocks would be very useful to an investment Client (not to mention profitable to an investment Advisor).
I suppose options could function as a leverage-based proxy for individual stocks. Not quite what you're after, especially given the time expiration factor, but a reasonable way to get near what you want to do, perhaps!
Best,
AIMster
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