Why were many brokers financially ruined by the stock market crash?

Many brokers were financially ruined by the Stock Market crash due to the widespread practice of buying on margin, where they borrowed money to purchase stocks. When stock prices plummeted, brokers faced massive losses on these leveraged investments, leading to margin calls that they couldn't meet. Additionally, the sudden loss of confidence in the market caused a panic sell-off, further exacerbating their financial woes and leading to insolvency for many. The crash ultimately triggered a broader economic downturn, compounding their difficulties.