One of the most-feared quirks of cryptocurrencies is becoming more of a headache.
Such 51 percent attacks, in which so-called miners gain control of the majority of the network’s computing power to falsify transactions, are generating ill-gotten gains that risk collapsing the value of the coins. Under attack for more than a week, Bitcoin Gold is down about 25 percent since May 18.
Similar attacks have targeted Verge, Monacoin and Electroneum, according to Autonomous Research LLC. To gain power over a coin with a market cap of $500 million, an attacker may need to spend as little as $778 an hour, according to Autonomous.
After all, many of these smaller coins — and there are now more than 1,600 of just the major ones — have ballooned in value, becoming valuable targets for criminals. Some bad actors also may want to torpedo one coin to boost the value of another, Spencer Bogart, partner at Blockchain Capital LLC, said in an email.