payment index Herrick (Herrick Payoff Index, HPI) confirms the strong trends and helps determine when they change its direction; monitors prices, trading volume and open interest (existing commitments), combining them into a single index. In MetaTrader 5 Herrick index can be displayed as a bar graph or a line graph for all trading tools, which translates open interest. Existing commitments or open interest - a total amount of existing contracts (futures and options) on which the calculation In this case, using the Herrick Payoff Index effectively would involve looking for divergences between the spiky advances in gold and the HPI indicator. For example, if gold futures appear to successfully test the April highs (just above 306 for continuous futures), while the HPI continues to fall, The Herrick Payoff Index is designed to show the amount of money flowing into or out of a futures contract. The Index uses open interest during its calculations, therefore, the security being analyzed must contain open interest. The Herrick Payoff Index was developed by John Herrick.