Alpha’s not easy to come by. Nor should it be. Once the exclusive purview of mutual funds, alpha is nowadays sought by exchange traded funds as well. Not too many, mind you. Of more than 2,200 ETFs, only 273 are deemed actively managed. That ought to make short work searching for alpha.

And, indeed, the list is short. According to Morningstar, only 54 active ETFs—some 20 percent of the bunch—produced positive alpha over the past 3 years. The five best delivered a 14.97 weighted-average alpha coefficient versus the S&P 500. That’s pretty impressive. But how does that stack up against the alpha earned by actively managed mutual funds?

When we set out to answer that question, we found it necessary to put mutual funds, as much as possible, on the same footing as exchange traded funds. We screened the galaxy of over 25,000 portfolios for ETF-like characteristics, such as being open to new investors and carrying a low minimum investment threshold. Most important, of course, was alpha positivity. Taking out the 254 portfolios classified as index funds, we whittled down the number of stars to 1,298, some 35 percent of the final field. Among these, the top five served up a weighted average 17.73 alpha factor.

All this points to the rarity of positive alpha and seems to give the edge to mutual funds when it’s found. But that’s not the end of the story; it’s worth looking at the field to see which funds delivered the greatest alpha and at what cost.

Most notably, the ETF table’s capped by three technology funds managed by New York-based ARK Investment Management LLC. The ARK Web x.0 ETF (NYSE Arca: ARKW), a portfolio capitalizing on cloud and mobile computing, and its stablemate, the ARK Innovation ETF (NYSE Arca: ARKK), a fund that exploits industrial innovation, genomics and web technology; both scored double-digit alpha coefficients. The No. 3 slot was filled by the ARK Industrial Innovation ETF (NYSE Arca: ARKQ) which focuses on technologies such as manufacturing automation, 3-D printing, electric vehicles and the like.