A girl poses for a photograph on a stone sphere monument that unidentified persons have painted with the white Bitcoin cryptocurrency symbol in Oktyabrskaya Square, Yekaterinburg, Russia.

For hedge funds, 2017 ended with a clean sweep — positive returns in every month that resulted in the best total performance in four years.

That kind of a winning streak hasn't happened since 2013 and was part of a 14-month run of monthly growth that resulted in a gain of 8.5 percent for the HFRI Fund Weighted Composite Index, an industry barometer of total hedge-fund performance. The index rose 0.9 percent for December.

The relatively strong overall performance for the year, though, was dwarfed by returns from the HFR Blockchain and HFR Cryptocurrency indexes, the latest additions to the hedge-fund universe.

Launched publicly in December, the indexes track managers who are investing in bitcoin, ethereum and others in the cryptocurrency space, as well as companies involved in blockchain and related technologies.

The blockchain index surged 88.5 percent in December and would have risen 2,690 percent for the year. Separately, the cryptocurrency index rose 88.4 percent in December and 3,175 percent for all of 2017.

"The powerful combination of surging global equity markets, dynamic M&A trends, commodity volatility and divergent interest rate cycles has created an exciting opportunity set for hedge funds coming into 2018," HFR President Kenneth J. Heinz said in a statement.

"Developing opportunities in risk parity, blockchain and cryptocurrency trading, each of which have posted outstanding performance in 2017, are likely to further complement and contribute to record industry growth in 2018," he added.

Of course, hedge funds continue to underperform the broader market. The was up about 19 percent for 2017 — 21.8 percent including dividends.

For hedge funds, fundamental growth proved to be the best strategy for the year, with an 18.9 percent gain. Health care rose 17 percent.

Betting against the market proved to be the worst strategy, with the HFR Short Bias index down 10.2 percent.