Bitcoin price historically rose after Halving (also, Halvening) dates. Fundamentally, halving dictates, every apprx. 4 years the amount of newly mined Bitcoins is reduced by 50%
2009: Start: 50 BTC per block November 28, 2012: The first Bitcoin halving takes place: 25 BTC per block July 9, 2016: Second halving: 12.5 BTC p.b. 2020: The third halving: 6.25 BTC (approximately 12th May)