The second week of August saw yet another massive selloff across the entire cryptocurrency market after the Securities and Exchange Commission (SEC) announced that it would postpone the decision on whether to allow the listing of the Cboe VanEck/SolidX ETF backed by Bitcoin (BTC) to September 30. Since that time, Bitcoin briefly fell below $6,000 on Friday with altcoins faring far worse, as more than 10% of the total market capitalization was wiped out in a matter of days.

The bearish price action occurred despite a relatively positive week of news coming from the major banks. Goldman Sachs (GS  ), one of the largest investment banks in the world, announced that it is currently exploring a plan to offer custody services to cryptocurrency funds and institutional clients. Barclays (BCS  ), the British multinational investment bank and financial services company, is also reportedly following other major financial institutions in building a cryptocurrency trading desk, as revealed by two traders at the bank.

Here is the rest of the week in review:

Facebook (FB  ) initially revealed last May that its experimental blockchain group would be led by David Marcus, the executive formerly in charge of Facebook's Messenger group. Marcus has been serving on Coinbase's board of directors since last December, but on Friday, he announced that he will be stepping down to focus on Facebook's new blockchain initiative.

Global equity markets struggled to close out the week after the Turkish lira dropped 17% against the U.S. dollar, sending the lira to its lowest point against the dollar in history. A recent Coindesk report noted that Turkish cryptocurrency exchanges saw a spike in volume on Friday. While the overall size of these exchanges is relatively small, with only $11.6 million in daily trading volume, each has seen at least a 100% increase in activity.

Ethereum Classic (ETC) became the fifth digital currency added to Coinbase after trading began this week on the Coinbase Pro platform, the company's new professional interface built on top of the existing GDAX trading engine. Robinhood added ETC one day earlier, and its price briefly popped up with the news.

Overstock (OSTK  ) shares surged more than 20% Thursday after the company revealed that its subsidiary tZero, a blockchain platform for capital markets, has secured a $270 million investment from GSR Capital, a private equity firm organized in Hong Kong.

A recent analysis conducted by the Wall Street Journal shows that dozens of pump-and-dump trading groups have routinely manipulated the prices of cryptocurrencies on large online exchanges to an amount of at least $825 million in the past six months. These activities have been directly responsible for the loss of hundreds of millions of dollars in counterparty trades.

Crypto prices plunged to test the critical $200 billion level before a slight bounce. The biggest losers are IOTA (IOTA), down 41 percent, Nebulas (NAS), down 39 percent, and Elastos (ELA), down 35 percent. The biggest winners are InflationCoin (IFLT), up 2,155 percent, Global Currency Reserve (GCR), up 106 percent, and Peercoin (PPC), up 69 percent.

The author owns a small amount of BTC and IOTA.