ARK Invest, the fund's parent company, did not respond to a request for comment. Overall, 2023 has seen investors back away from equity funds despite the stock market's rebound, in part due to high yields in the fixed income market offering a compelling alternative, said Todd Rosenbluth, head of research at VettaFi.

Domestic equity funds and ETFs posted a total of $151.3 billion in outflows year to date through June 7th, according to data from trade group the Investment Company Institute. In ARK's case, the dearth of inflows may also have to do with the behavior of individual investors, who make up a significant chunk of the fund's shareholders and have been loath to return after many were badly hurt when it fell by as much as 60% last year, Rosenbluth said. "Many investors have lost patience with the ARK ETFs and have moved on to other strategies following the prior period struggles," he said. "Those that stayed loyal ... are not seeming eager to add more exposure." Still, the recent broadening of the equity market's rally this year out of a handful of megacap stocks could mean investors will eventually give Cathie Wood's flagship fund another look, said Virag Shah, portfolio strategist at Van Leeuwen & Company.

Optimism among individual investors vaulted to a 19-month high in the latest American Association of Individual Investors (AAII) Sentiment Survey. Bearish sentiment plunged to a 19-month low.

Morgan Stanley analysts, meanwhile, wrote this week that retail and institutional investor sentiment has reached its highest levels in over two years and registered readings in the top quintile of the past several decades.

"Once you see the market concentration broadening out, we think you will see the investor flows follow," potentially sending more investors into ARK, Shah said. ARK's 2023 rally has largely been powered by the more than 100% gain in top holding Tesla Inc, which makes up roughly 12% of its assets. Shares of the company fell nearly 5% Wednesday as concerns about higher interest rates weighed on growth stocks.

Other positions in the fund include streaming company Roku Inc and cancer diagnostics company Exact Sciences Corp, which are both up more than 50% over the year to date.

(Reporting by David Randall; Editing by Ira Iosebashvili and David Gregorio)

By David Randall