The so-called increase in the collection of margin is actually to increase the level of margin ratio. Because futures trading is not carried out with full margin, only a certain proportion of contract value can be paid. As the delivery month approaches, the futures exchange will increase the level of this margin ratio, for example, from the original 10% to 12% (generally, the proportion of physical delivery will be higher when the contract expires, and it will be relatively low if it is cash delivery). Futures speculation is not necessarily for delivery. Most futures contracts that should be delivered in kind usually close their positions before expiration, the most obvious being commodity futures. The reason is that even the hedging buyer must make physical delivery in the commodity futures warehouse, and these warehouses are not necessarily convenient or costly for the buyer, so physical delivery is not necessary. For example, treasury bonds futures, due to the problem of conversion coefficient, have the problem of low actual market value of delivered bonds, which will also make futures buyers more inclined to close their positions before due delivery.

Breach of delivery must have happened. In recent years, the big derivative default is the bankruptcy case of investment bank Lehman Brothers. At that time, in 2008, the HKEx closed the relevant futures contracts in the Hong Kong market (at that time, the news said that the HKEx lost hundreds of millions, but I don't remember how many hundreds of millions it actually lost, it seems to be 200 million), and the funds for its liquidation mainly came from the relevant guarantee funds for futures trading. General futures fairs charge a very small percentage of relevant protection fund fees under general trading conditions, mainly to prevent one party from defaulting, and the exchange can have enough contracts of the defaulting party in capital settlement.