By Dan Weil At a Wells Fargo conference ‘large-cap banks showed conviction that core pre-tax operating margins will improve.’ Renowned bank-stock analyst Mike Mayo of Wells Fargo has put together a list of some of his favorite picks. At a recent Wells Fargo banking conference, he outlined some the names he included. “Large-cap banks showed conviction that core pre-tax operating margins will improve—a contrast to other industries,” he wrote in a commentary. “What’s noteworthy is that, despite the fear in stock prices, the boogeyman was a no-show for all of our meetings.” The KBW Nasdaq Bank sto…