The day-ahead contract reached its maximum on July 5, rising to $466 per thousand cubic meters.
The gas price with delivery on Thursday at the TTF hub in the Netherlands dropped to $398.
The two-year agreement concerns the financing of gas trading operations.
The spot gas price fell 11% in one day following the correction in oil prices.
On Monday, booking auctions for gas transmission capacities for the coming and subsequent years were held throughout Europe.
At the beginning of July, natural gas stocks in Ukrainian UGS facilities amounted to 16 billion cubic meters.
The price of gas for delivery on Friday at the TTF hub in the Netherlands closed at $450 per thousand cubic meters.
The major pipelines for the delivery of Russian gas, Nord Stream and Yamal-Europe, will be under repair in half of July.
The balance of the European gas market is getting tenser due to the uncharacteristic seasonal pattern of a decrease in LNG supplies.
Earlier this year, the company did not book interruptible capacity, as it did with the auctions for May and June.
Gas stocks in Ukrainian underground storage facilities increased by 1% from 20 to 28 June.
Now the import is only 3 million m3 per day.