The stock market turned south today, with financial shares tanking hard. JPMorgan Chase's top brass threw down a warning—President Trump's push to cap credit-card interest rates could seriously squeeze the banking sector. It's not hard to see why traders got spooked. When you cut into lending margins like that, profit margins get squeezed. The selloff hit financial stocks particularly hard, dragging down the broader market. For investors watching sectors like banking and consumer finance, this is the kind of policy curveball that can reshape entire corners of the market. Whether this proposal gains traction or fades remains to be seen, but the initial market reaction tells you everything about how Wall Street feels about it.