Ideally any broker worth his salt should have reduced leverage or margin on a day like this. Let me explain why.
When a brokerage gives additional leverage, he is doing it from his working capital. Assume a brokerage allows you to buy Nifty future at 20k margin whereas exchange asks for 50k, he is essentially providing this 30k from his money. Such leverage is typically provided only for intraday trading.
Now let me explain with an example, assume Nifty is at 8000 and a client has taken a long position with 20k in the account. If nifty falls 300 points, the loss made is 22500, but the client has only 20000. Where does this extra Rs 2500 come from? The exchange will take money from the broker immediately, what if the broker is not able to recover this Rs 2500 loss from the client. What if Nifty falls down 500 points? That is a loss of 17500 more than what the client has in his account. Assume 500 clients lost Rs 17500 each more than the money actually in the account, or a loss of Rs 87.5lks together, what if the broker doesn’t have this much of his own money?
If he doesn’t, he is taking a systemic risk for all his other clients who have money. The risk is significantly higher with smaller brokers whose own capital/networth is much less ( Rs 1 crore to Rs10 crores kinds) and give high leverages immaterial of the current or expected volatility in the markets.
It is similar to a bad bank which gives loan to businesses without analysing economic conditions, or gives loan to earn revenue without worrying about the risk. If such loans turn into NPA’s, all depositors money is at risk. In case of banks, govt jumps into help, but not for brokerage firms.
Exchange margin requirements is meant to ensure such things don’t happen. It is meant to ensure that if a client loses money, he can lose only to the extent of money in his trading account in a day. The SPAN+Exposure covers for the highest fall that has happened on the exchanges for a while. But exchange margin goes up only after volatility happens on the exchange. It is not smart enough to go up before the event. So in the case of Brexit, coming into the event, there was hardly any volatility, so exchange margin requirements had more or less remained steady.
Nifty falling 500 points in a few minutes, is not really a daily affair, typically happens once or twice in 5 to 7 years. That is why most brokerages give that additional intraday leverage over and above what F&O already gives. But I guess everyone understands, that the day Brexit happened, it could have been one of those days. As a brokerage, it is important to be safe than sorry. It is important that a few people don’t put systemic risk on everyone else. So yes, we could have earned more brokerage revenue by giving that additional leverage, but we haven’t built this business by compromising on risk.
Like I said earlier, almost every brokerage worth his salt around the world reduced trading leverages on this day after the Brexit news.