When a mutual fund advertises a 5-star Morningstar rating, most investors assume it means this is a great fund to invest in. The reality is significantly more nuanced — and misunderstanding ratings can lead to poor investment decisions.
Morningstar's star rating is a backward-looking, risk-adjusted performance score. It compares a fund's historical returns against its peers in the same category. A 5-star fund has delivered better risk-adjusted returns than 90% of its category peers over the past 3, 5, and 10 years. The critical word is historical.
Research consistently shows that funds rated 5 stars often see significant inflows — and subsequently underperform. Why? Because they've already had their strong run. Size itself can become a headwind. And mean reversion is real in financial markets.
A fund that moves from 3 stars to 5 stars has already delivered the performance. You're arriving at the party after it peaked.