This is a proprietary Morningstar data point. Morningstar rates mutual funds and ETFs from 1 to 5 stars based on how well they've performed (after adjusting for risk and accounting for sales charges) in comparison to similar funds and ETFs. Within each Morningstar Category, the top 10% of funds and ETFs receive 5 stars and the bottom 10% receive 1 star. Funds and ETFs are rated for up to three time periods three-, five-, and 10-years and these ratings are combined to produce an overall rating. Funds and ETFs with less than three years of history are not rated. Ratings are objective, based entirely on a mathematical evaluation of past performance. They're a useful tool for identifying funds and ETFs worthy of further research, but shouldn't be considered buy or sell signals.