For enthusiasts of Bitcoin, a once-every-four-years software update called the "halving" has long been held as one of the keys to propping up its value. This time around, it's also set to trigger multibillion-dollar declines in revenue for the very companies that ensure the digital currency's smooth functioning, right on the heels of a surge in their biggest costs. Around April 20, the halving will cut the amount of Bitcoin that "miners" can earn each day for validating transactions to 450 from 900 now. Based on Bitcoin's current price, it could spell revenue losses of around $10 billion a year for the industry as a whole. Marathon Digital Holdings, CleanSpark, and other miners, which compete for a fixed Bitcoin reward by solving mathematical puzzles using superfast computers, have invested in new equipment and sought to buy smaller rivals in an attempt to cushion the drop-off in revenue.