Are you wondering what whales are coming out? Or do they sell in the previous period?
It is this indicator of the open interest index, which drools the whales in the futures market.
When open interest is high (as shown in green), it means that there is a large amount of open contracts (puy positions) in the market.
Whales monitor these levels because they know that large price movements will lead to liquidations of these contracts, in the opposite direction.
For example, if the open interest is high in the buying trend, whales may suddenly try to push the price down, causing the liquidation of positions to buy.
This leads to a large selling wave that may further fall the price, allowing whales to buy at lower levels.