Oct 26 (Reuters) - Robinhood Markets Inc (HOOD.O) reported a jump in third-quarter revenue on Tuesday, as cryptocurrency trading helped offset the hit from retail investors becoming less active after a frenzied rally in shares of so-called "meme stocks" earlier this year. Robinhood, in its second set of results as a public company, posted total revenue of $365 million for the quarter ended Sept. 30, compared to $270 million a year earlier.