Bitcoin halving is an event that occurs approximately every four years (every 210,000 blocks), where the reward for mining new blocks is halved, effectively reducing the rate at which new bitcoins are created. This process is a key feature of Bitcoin's design, ensuring its limited supply, and happened already three times, according to the schedule.

This market will resolve to the UTC calendar day, when Bitcoin's block #840,000 ("halving" moment) will be mined.

https://www.bitcoinsensus.com/bitcoin-halving-countdown/

https://www.coingecko.com/en/coins/bitcoin/bitcoin-halving

https://www.bitdegree.org/halving/next-bitcoin-halving-dates

https://timechaincalendar.com/en/block/840000