The cryptocurrency markets are having their worst day in some time on Tuesday. Not only are bitcoin (BTC-USD) and Ethereum (ETH-USD) down, or a few other major cryptocurrencies, but digital currencies are largely plunging across-the-board. In all, the cryptocurrency market has lost about $70 billion in value over the past 24 hours.

The stock market's correction over the past couple of days could certainly be playing a role in the decline. In addition, a few troubling news items seem to be worrying cryptocurrency investors, which may be causing selling pressure.

A person staring at a red arrow on graph trending sharply downward.

Image source: Getty Images.

Today's cryptocurrency prices

Here's a look at the five largest cryptocurrencies by market capitalization, and how much each has changed over the past 24 hours.

Cryptocurrency Name (Code)

Price in U.S. Dollars

Day's Change

Bitcoin (BTC-USD)

$9,936

(12.5%)

Ethereum (ETH-USD)

$1,042.60

(11.6%)

Ripple (XRP-USD)

$1.10

(15.4%)

Bitcoin Cash (BCH-USD)

$1,476.20

(11.6%)

Cardano (ADA-USD)

$0.50

(17.1%)

Data Source: investing.com. Prices and daily changes as of Jan. 30, 2018 at 2:15 p.m. EST, and prices are rounded to the nearest cent where appropriate.

Cryptocurrency prices are down pretty much across the board. In fact, all of the top 20 cryptocurrencies are down on Tuesday. Bitcoin (BTC-USD) dropped below the key $10,000 level, and other leading cryptocurrencies were also plunging. Of the top five, only Ethereum (ETH-USD) remains in the green over the past week.

Subpoenas are scaring investors

One reason for the widespread decline was a Bloomberg report that a pair of subpoenas were issued to cryptocurrency-related companies. Cryptocurrency exchange Bitfinex and coin issuer Tether were reportedly sent subpoenas on Dec. 6.

If you're not familiar, Tether's digital currency is supposedly backed by the U.S. dollar, and the company claims that each of its coins are backed by U.S. dollars held in reserve -- in other words, each of Tether's coins is supposedly worth $1. As of this writing, this means that the company should have roughly $2.3 billion (in U.S. dollars, not in digital currencies) in reserve, although no evidence has been provided and many doubt that the money is actually there.

Both Tether and Bitfinex have the same CEO and also share some other corporate officers.

SEC freezes a huge ICO

Initial coin offerings, or ICOs, have been the subject of several warnings to consumers by the Securities and Exchange Commission (SEC).

On Tuesday, the SEC announced that it would be freezing the assets of Dallas-based AriseBank, and would be halting its ICO. According to the complaint, the bank "used social media, a celebrity endorsement, and other wide dissemination tactics to raise what it claims to be $600 million of its $1 billion goal in just two months." It also said that because the ICO was never registered with the SEC, it constitutes an illegal offer to sell securities.

AriseBank, which refers to itself as a "decentralized bank," is also accused of falsely claiming that it purchased an FDIC insured bank, through which it could offer customers insured deposit accounts.

Adding to investor uncertainty

The bottom line is that there are several things going on in the cryptocurrency market that seem to be adding to investor fears. This, combined with an absence of recent positive catalysts, is likely the force pushing the cryptocurrency markets lower Tuesday.

Matt Frankel has no position in any cryptocurrencies mentioned. The Motley Fool has no position in any cryptocurrencies mentioned. The Motley Fool has a disclosure policy."