I was going to post this because I hadn't yet seen the word 'prospectus' in this thread, maybe it's still worth posting after Jim's post:

Read the prospectus!
Look for red flag words like "up to X% of the fund invested in SAFE STUFF", and "at the manager's discretion, the fund may invest up to Y% in LONG LIST INCLUDING SWAPSetc".

I once bought an investment grade bond fund (many years ago) that was receiving a lot of press because it was actively managed by a well-know person, was doing well, and had low fees.

What could go wrong?

It started not to do well.

I then looked at the holdings -- he was shorting the S&P. In a bond fund.
I then looked carefully at the prospectus, and saw words similar to the earlier quotes about "manager's discretion".

Learned two lessons (1) don't reach for yield (2) read the prospectus