ARK Investment Management has been one of the ETF marketplace’s biggest winners this year. The tiny New York-based ETF house started the year with under $100 million in assets between its five funds. Today, that number has leapt to more than $700 million and growing. Its worst-performing fund, the 3D Printing ETF ( PRNT ), is up only 19% on the year. The other four are all up at least 45% year-to-date. All are driven by disruptive technology along with the sixth ETF, which makes its debut this week.