As part of Morningstar's "Mind the Gap" series

Where they investigate why investors actual returns lag that of the underlying things they are investing in - focused mainly on collective investment vehicles like managed funds and ETF's

They've just released a new update titled "Why investors missed out on 15% of total fund returns" (I've linked to the public version of the article)

Imagine you invest in a fund. Over the next 10 years, it generates a 7.3% total return per year after fees. Not bad. But when you check your brokerage statement and do the math, you find you earned about 1.1 percentage points per year less than that. What gives?

It was interesting that even index ETF investors underperformed those ETF's actual performance, and even a bit more so than investors in open ended (index) funds - I'm presuming because ETF's are so liquid impatient "investors" can trade in and out of them on whim and thus underperform more through bad decisions, poor timing, fees and transaction costs, etc