Bitcoin (BTC-USD) dropped below $6,000 on Thursday and is currently trading at approximately $5,900 on Friday -- its lowest level since November 2017, when the cryptocurrency boom was just ramping up.

Before we take a closer look at bitcoin's declining price and what could be causing it, here's an overview of the latest cryptocurrency price action. Here's where the 10 largest cryptocurrencies by market capitalization stand and how much they have fallen over the past 24 hours, as well as over the past week.

Stacks of gold coins with bitcoin symbol.

Image Source: Getty Images.

Cryptocurrency Name (Code)

Price in U.S. Dollars

Day's Change

7-Day Change

Bitcoin (BTC)

$5,908.60

(3.4%)

(5.2%)

Ethereum (ETH)

$412.50

(5.7%)

(13.6%)

Ripple (XRP)

$0.43

(6.5%)

(13.1%)

Bitcoin Cash (BCH)

$661.50

(5.5%)

(15%)

EOS (EOS)

$7.35

(7%)

(17.7%)

Litecoin (LTC)

$73.66

(7.9%)

(14.5%)

Stellar (XLM)

$0.17

(9%)

(15.7%)

Cardano (ADA)

$0.12

(7.4%)

(18.1%)

Tether (USDT)

$1.00

0%

(0.3%)

IOTA (MIOTA)

$0.91

(6.3%)

(10.7%)

Data source: www.investing.com. Prices and daily changes as of June 29, 2018, at approximately 11:50 a.m. EDT, and prices are rounded to the nearest cent where appropriate.

One interesting thing to note is that there's a newcomer -- Tether -- in the top 10 and that it's the only one that's not in the red today.

There's a good reason for this. Tether is directly tied to the U.S. dollar (notice that one Tether token is worth exactly one dollar), and therefore does not rise and fall along with the other cryptocurrencies. In fact, the only reason Tether has become one of the largest cryptocurrencies is because the others have performed so poorly while it has remained constant at $1.00 per token.

A sustained downtrend with no end in sight

Perhaps the most troubling part of the decline is that there aren't any major news items weighing on the price of bitcoin (BTC-USD). Rather, this is simply a continuation of a downtrend that has lasted for almost two months and isn't showing any signs of stopping. After a recent peak of nearly $10,000 in early May, bitcoin has steadily shed about 40% of its value.

Bitcoin Close Price Chart

Bitcoin Close Price data by YCharts.

It's not just bitcoin

Another trend worth noting is that other cryptocurrencies have performed poorly as well -- even worse than bitcoin (BTC-USD) in most cases. I mentioned that bitcoin has fallen by 40% since its recent high in May, but take a look at how some of the other leading cryptocurrencies have fared in that same time frame.

Cryptocurrency

Performance Since May 4, 2018

Ethereum (ETH)

(48.1%)

Ripple (XRP)

(50.2%)

Bitcoin Cash (BCH)

(62.4%)

EOS (EOS)

(58.3%)

Litecoin (LTC)

(57.9%)

Cardano (ADA)

(67.4%)

Data source: YCharts.

Could investors be losing interest?

There have been several issues weighing on the cryptocurrency markets over the past couple of months, so although there isn't anything that's causing today's drop, that doesn't mean the downtrend is completely without catalysts.

For example, about a week ago, Japan's financial regulatory agency ordered several exchanges to improve certain anti-money-laundering practices. There have also been a couple of major hacking incidents in recent weeks that have spooked investors.

The key question is whether these events, as well as the roughly 60% bitcoin price decline so far in 2018, are causing investors and speculators to permanently lose interest in digital currencies. If cryptocurrency prices are to rise into five-digit levels again, it's fair to say that significant interest from new and existing investors will be required. So, if interest is fading, it's entirely possible that the downtrend in bitcoin and the rest of the cryptocurrency market could continue.