Hello
You can indeed buy and sell stocks and futures at the same time. Because mobile phones and computers are now very developed, you can buy stocks and sell futures at the same time.
Futures are the same as stocks. If you sell them, someone must buy them. Futures and stocks? There must be at least two parties to the transaction.
Futures are completely different from spot goods. Spot goods are real goods (commodities) that can be traded. Futures are not mainly goods, but are based on certain mass products such as cotton, soybeans, oil, etc. and financial products. Assets such as stocks, bonds, etc. are standardized tradable contracts. Therefore, the subject matter can be a certain commodity (such as gold, crude oil, agricultural products) or a financial instrument.