Peercoin, otherwise known as PPCoin and Peer-to-Peer Coin, has the third-biggest market capitalization after bitcoin and litecoin, according to coinmarketcap.com.
"Money the way it should be," says the sales pitch on its website. "It enables instant payments to anyone! No banks, no fraud, no hidden-fees," the company says.
Peercoin states that Bitcoin favors "proof-of-work," whereas Peercoin prefers "proof-of-stake." This means that people are given new coins if they already hold some, instead of giving new coins to people that have mined the currency. Thus, the fewer subsidies to miners, the less people would be inclined to try to complete the energy intensive tasks, making the currency more energy efficient.
Waller told CNBC that it's experimental, but it seems sound. It's a "very speculative investment. I have some because 'you never know,' " he said.