1. Bitcoin chills: Bitcoin prices are slumping again after South Korea announced a clampdown on the cryptocurrency.

The country's government said Thursday it was putting in place measures to cool speculation in bitcoin, which has surged by more than 1,300% in 2017.

The measures include a ban on opening anonymous virtual currency accounts and new laws giving authorities the power to shut down digital currency exchanges.

Bitcoin's value plunged more than 10% to below $14,000 on Thursday morning in Asia, according to CoinDesk.com, and continues to be volatile.

2. Dollar dip: The U.S. dollar has been steadily weakening this year and the trend is continuing this morning. The greenback is down by about 0.4% versus many major global currencies, including the euro, British pound and Canadian dollar.

The U.S. dollar index -- which tracks the dollar's performance versus global currencies -- is down by about 11% from its peak at the start of the year.

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3. Global stock market overview: U.S. stock futures are indicating stocks could have a positive day on Thursday, but the gains could be very small.

European markets are mostly dipping in early trading, though the moves are modest.

Most Asian markets ended the day with gains.

This follows quiet holiday trading in the U.S. The Dow Jones industrial average, S&P 500 and Nasdaq all eked out tiny gains on Wednesday.

Trading volume at this time of year is usually low.

The top U.S. indexes are all up by 20% to 29% in 2017.

Related: The best global stock markets of 2017

4. Coming this week:

Thursday -- Weekly U.S. crude inventories report out at 11 a.m. ET
Friday -- Russia reports latest quarterly GDP