The value of all cryptocurrencies moved above $350 billion Thursday, with bitcoin — which accounts for more than 40% of all 1,575 digital currencies — recording back-to-back winning days.

A single bitcoin BTCUSD, -0.27% was last valued at $8,237.18, up 1%. However, for the second day running, bitcoin underperformed its smaller coin cousins, known as altcoins.

The highlight of trading this week has been the prevalence of short-term price fluctuations.

What’s with all this short-term volatility?

As highlighted Tuesday, one explanation for the volatile price changes could be large, one-time trades, often conducted by large holders referred to as bitcoin whales.

Read:Bitcoin whales dump $100 million of digital currency in 24 hours

Beginning early Monday, the price of bitcoin has experienced numerous moves of more than $200 a coin inside a period of 20 minutes. However, one digital-currency trader said liquidity remains the driver of prices.

“We see this is as business as usual for the digital-currency land,” said Martin Garcia, managing director and head of sales and trading at Genesis Trading. “What it does show is that liquidity is still tight and it doesn’t take too much activity to move the prices.”

Kraken is first exchange to fight N.Y. attorney general request

San Francisco-based Kraken became the first cryptocurrecy exchange to push back against the New York attorney general’s request for information.

On Tuesday, Eric Schneiderman’s office sent a questionnaire to 13 digital-currency exchanges seeking information to help improve transparency and better protect investors. Initial reaction was supportive, with major exchanges Coinbase, Bitfinex and Gemini all expressing a desire to work closely with regulators and officials to better serve the industry.

However, it a tweet Thursday, Kraken CEO Jesse Powell said the questionnaire was an intrusion and called the attorney general’s office tone-deaf.

“Legitimate entities generally like to demonstrate to their investors that their money will be protected. This is very basic information that any credible platform should have on hand and be willing to share with their investors,” wrote Amy Spitalnick, press secretary to the New York attorney general, in an email to MarketWatch.

Altcoins on the move

The altcoin market continued its charge Thursday. Ether was higher by 7% at $560.61; bitcoin cash, which rose more than 15% Wednesday, was up 9.5% at $972.92; Litecoin added 4.1% to $145.73; and Ripple’s XRP remained above 70 cents, last trading at 75 cents, up 6%.

The Cboe’s May futures contract US:XBTK8 closed up 1.5% at $8,250 and the CME Group Inc. April contract US:BTCJ8 finished the day at $8,260 up 1.7%.

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