Cathie Wood sold 90% of her Twitter stock this year. Then Elon Musk sent the shares soaring — and her stake would be worth $700 million if she'd held onto it.

The star stock-picker has not had a great start to the year. Her flagship ARK Innovation fund has lost 40% so far this year, compounding the 24% drop last year.

When waves of cheap cash sent the kind of speculative technology stocks she invests in into the stratosphere, her funds shot to prominence.

As money conditions have tightened, interest rates have gone up and the tech sector has lost some of its luster, Wood's funds have struggled.

ARK Invest buys and sells stocks to manage its portfolio. The company sold most of its holdings of the micro-blogging platform this year, missing out on the huge rally that ensued after Musk revealed a majority stake in the company.

A filing with the securities regulators shows that Musk bought a 9.2% stake in the company for around $3 billion, making him its largest shareholder. He joined the board.

The news sent the shares of the company up 27% on the day, to three-month highs. The stock is now around $47.

ARK had already sold most of its holdings.

According to data from trading tracker Cathie's Ark, ARK's funds held over 15 million shares of the micro-blogging site at the beginning of the year. The holding was close to 1.3 million shares by April 7.

If ARK had kept its stake in the social network, it would now be worth over $700 million, compared to its current holdings of $62 million.

Wood invested a lot in the social networking site. ARK bought more than 1 million shares worth almost $50 million after Jack Dorsey resigned.

Wood still believes that Musk has the potential to shake up the social networking site, even though she has trimmed her holdings of the electric vehicle company.

She said this could be setting up for another leadership change.

The ARK Innovation fund experienced its worst decline in its history in January, when tech stocks got hammered and the Nasdaq 100 saw its biggest monthly drop in three years.

The undervaluation in Ark's portfolio holdings reached an extreme I have never experienced in my career.

She believed that the rubber band would snap and the performance would rebound.