First of all Schwab and IB are not banks. Second, their business model is different. They are not directly investing in SVB; they are agents who facilitate investments in SVB so they should be isolated from SVB. Not really sure why IB's shares would decline because of this. And not even sure why the four largest banks and brokerages like JP Morgan and Bank of America would be affected. Their shares dropped even more than IB's.
SVB is just a local Californian bank. And it's a very specialized bank that's almost exclusively invested in the high tech. and IT industry. Before this, nobody's even heard of this bank. Its market cap is 6.27B, comparing to JP Morgan's 393.38B and Bank of America's 242B, it's a drop in the bucket. Even IB's market cap is 33B and Schwab's eve larger at 101B. All of these banks and discount brokerages are well diversified in all segments of the business and variety of market sectors. I have money with IB and I am not withdrawing. Why would I need to withdraw? What am I going to do after I withdraw my money? I need to trade.
People just need to chill.