Yes, ForecastEx contracts pay an incentive coupon based on the closing market value of the positions. The incentive coupon accrues daily and is paid monthly. Incentive coupons are currently paid at the IBKR Pro USD benchmark rate minus 50 bps. To view the current rate please reference the Global Interest Rates page and look under IBKR Pro USD balances in excess of 10,000.
Example: If you purchase a position at USD 0.50 and the market closes at USD 0.50, the daily incentive coupon will be based on USD 0.50. If, on the following day, the market for the same contract closes at USD 0.70, the daily incentive coupon will be based on USD 0.70.