The cryptocurrency market is starting the week off strong.

Bitcoin, the largest cryptocurrency by market value, hit a more than three-month high on Sunday, topping $50,000, and is trading at around $49,600 as of Monday afternoon.

Other top cryptocurrencies, like ether, cardano and dogecoin, are up as well, with the value of the entire cryptocurrency market at over $2.15 trillion, according to CoinMarketCap.

Between Visa buying a CryptoPunk non-fungible token, or NFT, for six figures and Twitter and Square CEO Jack Dorsey trying bitcoin mining, here are six things that happened in the crypto space this past week.

1. Jack Dorsey says he is ‘trying’ bitcoin mining

It's no secret that Jack Dorsey, CEO of Twitter and Square, loves bitcoin. He has touted it as the most important project in his lifetime to work on, and Square, his digital payments company, bought over $170 million worth of bitcoin earlier this year.

Now, the billionaire CEO is mining it, too. "I'm trying mining with @compass_mining," Dorsey tweeted on Tuesday.

Compass Mining is a service that hosts, supplies and operates cryptocurrency mining rigs for individual miners who do not want to worry about purchasing and maintaining mining equipment themselves.

Bitcoin operates on a proof of work model, where miners must compete to solve complex puzzles in order to validate transactions. The process isn't easy: It requires a lot of energy and computer power, which isn't cheap. The computers themselves, along with other equipment, can also be very expensive.

2. Robinhood says dogecoin accounted for 62% of crypto revenue in Q2

In its first earnings report since its IPO last month, Robinhood said that cryptocurrency accounted for more than half of all transaction-based sales in the second quarter.

Dogecoin, a meme-inspired cryptocurrency that started as a joke, accounted for 62% of its crypto revenue, Robinhood reported.

In total, its revenue from crypto transactions was $233 million in the second quarter.

3. Coinbase is buying $500 million in crypto on its balance sheet

On Thursday, Coinbase announced it is buying $500 million in crypto on its balance sheet and will allocate 10% of its quarterly profits into a crypto assets portfolio.

Coinbase plans to invest in "Ethereum, proof of stake assets, DeFi tokens, and many other crypto assets supported for trading on our platform," company finance chief Alesia Haas said in a blog post.

4. The world’s second-largest stablecoin is changing its makeup

In a blog post on Sunday, Centre, the consortium that developed stablecoin USD Coin, announced it's changing the makeup of its reserves once again.

This time, its reserves will consist of cash and U.S. Treasury bonds.

Stablecoins are cryptocurrencies that are supposed to be pegged to reserve assets like fiat currency. While the developers behind USD Coin previously said it was backed 1:1 by cash, it was revealed in July that cash made up just over 60% of its reserves. The other 40% was backed by debt securities and bonds.

USD Coin is the second-largest stablecoin, with $27 billion worth of coins in circulation.

5. Hacker behind $600 million crypto heist returns all stolen funds

Poly Network, a decentralized finance, or DeFi, platform was hacked earlier this month, with over $600 million worth of crypto stolen.

The hacker exploited a vulnerability in the platform's code, which allowed them to transfer the stolen funds. But as of Monday, Poly Network has recovered all of the stolen funds.

"At this point, all the user assets that were transferred out during the incident have been fully recovered," Poly Network said a blog post on Monday. "We are in the process of returning full asset control to users as swiftly as possible."

The person claiming to be the hacker said the theft was simply done "for fun."

6. Visa bought a CryptoPunk

Visa announced that it bought a CryptoPunk NFT for $150,000 in ether.

"Today, as we enter a new era of NFT-commerce, Visa welcomes CryptoPunk #7610 to our collection," the company tweeted on Monday.

CryptoPunks are an assortment of 24x24 pixelated avatars, each considered to be rare NFT collectibles. There are a total of 10,000 in existence and no two are exactly alike. Each has its own unique features and accessories.

"We think NFTs will play an important role in the future of retail, social media, entertainment and commerce," Cuy Sheffield, head of crypto at Visa, said in a blog post on Monday. "To help our clients and partners participate, we need a firsthand understanding of the infrastructure requirements for a global brand to purchase, store and leverage an NFT."

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