Julian Gingold, a stockbroker at UBS Group, has a simple formula for deciding whom to back in the Republican presidential primary: the most conservative candidate who can win. Anthony Scaramucci, who runs a hedge fund-of-funds business, likens the choice to picking a top executive. In their midtown offices and Upper East Side townhouses, Wall Street financiers are sizing up presidential candidates and laying their bets, often with the same dispassionate arithmetic they use to identify a stock that’s on its way up.