The charge paid by a speculator for non-settlement of his account within the specified period is

On a stock or commodity exchange, settlement day is the fixed date on which a speculator who has bought or sold on account must complete payment or delivery. Sometimes a speculator who has bought shares is not yet ready to pay and settle, perhaps because they are still waiting for the price to move in their favour, so they ask for the settlement to be carried over to the next settlement day.

The charge paid by that speculator to postpone settlement to the next account is called contango. It is essentially a fee for the privilege of delaying payment while still holding the position.

Backwardation is the reverse charge, paid by a seller who wants to delay delivering shares they have sold. Brokerage and commission are fees paid to the broker for arranging the transaction itself, not for delaying settlement, so they do not match what the question describes.

Keep the two terms apart by remembering who pays: a buyer delaying payment pays contango, while a seller delaying delivery pays backwardation.