International Bancshares Corporation (IBG), operating as a regional bank holding company, primarily engages in conventional banking activities that involve interest-based lending and deposits, rendering it non-compliant with core Shariah principles prohibiting riba. While financial screening ratios such as debt-to-market-cap (0.43%) and liquidity (0.66%) comfortably pass thresholds across AAOIFI, MSCI, and S&P standards, the interest income ratio of 4.76% is marginally acceptable but requires purification. The overriding concern is the business activity screening, where nearly 100% of revenue derives from non-permissible riba activities. No inclusion in major Shariah indices confirms the non-compliant status. Investors should avoid or monitor for any shift toward Islamic financing models.