In addition to increasing its purchases of bonds, Soros Fund also bought calls on Nio for the first time in the third quarter.

US billionaire George Soros' Soros Fund Management increased its bet on Nio in the third quarter, buying call options on the company for the first time.

The fund held 115,317,000 Nio assets called "NOTE 2/0" at the end of the third quarter, up 64,000,000, or 124.72 percent, from 51,317,000 at the end of the second quarter, according to a Form 13F filing on Monday.

Unlike other hedge funds whose positions are primarily in common stocks, Soros Fund's positions include a large number of alternative assets similar to these notes.

Assets labeled "Note" may be convertible senior notes of a company, and they are measured on Form 13F in "PRN", which stands for the principal amount on convertible debt securities.

Soros Fund first bought convertible notes of Nio in the first quarter of the year and increased its position in "NOTE 2/0" in both the second and third quarters.

At the end of the third quarter, the fund's holdings in Nio NOTE 2/0 were valued at $102 million, up 132.79 percent from $43.9 million at the end of the second quarter.

The fund also held Nio assets called "NOTE 0.500 percent 2/0", which numbered 25,330,000 at the end of the third quarter, down 46,566,000 shares, or 64.77 percent, from 71,896,000 at the end of the second quarter.

Overall, Soros Fund's bond holdings in Nio were valued at $122 million at the end of the third quarter, up $22.57 million from $98.95 million at the end of the second quarter.

Notably, the fund also held call options that could be converted into 200,000 shares of Nio ADS valued at about $3.15 million at the end of the third quarter, marking its first purchase of the asset.

Soros Fund does not currently hold any assets in Nio's local peers Motors or .

During the third quarter, Nio fell 27 percent.