Is 11% not a huge time value premium for something that expires in a month? Can we compare the time premium with the interest rate? I have traded options, but never futures. With options there several components that increase the premium besides just the time component.
According to [0] futures shouldn't have a time premium because both parties are obligated to to fulfill the contract.
As you stated in the OP, the 11% spread should be a "riskless" arbitrage. If so, I suspect that this spread will decrease.
It is a huge premium. In reality it should only be the future value of the current spot, given the current interest rate. For other types of futures (oil, grains) that have storage costs or seasonality there are other factors that affect the difference between the spot and future price, but for financial futures (especially cash-settled) it should be nearly no difference for a one-month expiry.
According to [0] futures shouldn't have a time premium because both parties are obligated to to fulfill the contract.
As you stated in the OP, the 11% spread should be a "riskless" arbitrage. If so, I suspect that this spread will decrease.
[0] https://money.stackexchange.com/questions/12359/do-futures-h...