That's basically right, but it depends on the description in the fund contract.

Because the index fund promises to fit the corresponding index and completely copy the trend of the corresponding index, it must hold the constituent stocks of the index as high as possible. However, due to the existence of daily subscription and redemption, index funds need to hold a small amount of cash to deal with daily redemption, so index funds are usually designed to hold about 90% or more positions. If it can't be realized, it will violate the original contract promise and bear the liability for breach of contract.