U.S. bank stocks continued outperforming the broader stock market in September.

While the S&P 500 declined by about 5% on a total return basis last month, the S&P U.S. BMI Banks index climbed 2.4%. The 208 banks in the S&P Global Market Intelligence analysis had a median return of 2.6%. Just two of the 20 largest banks by market capitalization at the end of September recorded negative returns: Citigroup Inc. and San Francisco-based First Republic Bank.

Texas Capital Bancshares Inc. had the worst monthly market performance in the analysis, down 11.7%. Shares in the Dallas-based bank fell sharply at the beginning of September after it disclosed a strategic transformation plan. It had announced a merger of equals with McKinney, Texas-based Independent Bank Group Inc. on Dec. 9, 2019, which was terminated May 22, 2020.

During the last 11 months, Texas Capital has traded at a discount to the industry median in terms of price-to-adjusted tangible book value. The average valuation gap on a month-end basis is 28 percentage points, with a peak of 49 percentage points at Sept. 30.

On the other hand, Independent Bank Group has consistently traded at a substantial premium to the industry. The valuation gap has ranged between 42 and 64 percentage points.

Click here to see S&P Global Market Intelligence's calculations for price-to-adjusted tangible book value as of Sept. 30.

Philadelphia-based Republic First Bancorp Inc. remained the lowest-priced bank by P/ATBV. The stock fell by 7.8% in September, dropping the valuation to 67.3%.

The two entrants to the bottom-20 valuation list were Texas Capital and Warsaw, N.Y.-based Financial Institutions Inc.

The exits were Millersburg, Pa.-based Mid Penn Bancorp Inc. and Boston-based Berkshire Hills Bancorp Inc.