How do I tell if a mutual fund is risky or not?

There are different implicit "risks"

the most important ones are:

that the active mutual fund manager very probably is not able to

beat a general stock market index, this is evidenced by several studies.

There are fund mangagers who beat a market.

But there are only very rare managers who beat the market on a long term base all things considered (particularly also that the mutual fund is compared to an appropiate market index, f.ex. a very technology heavy mutual fund cannot per se be compared versus SP500 index

the second "risk" is underperformance that is almost programmed into the mutual fund because of the currently high fees.

I recommend to read much on long term buy & hold passive indexing ETFs, in my view the most promising investing strategies for retail investors who want to participate in equity investing success

Hello!

You can look at;

1) Alpha

It is the measure of an invesment's performace on a risk-adjusted basis. the higher the alpha the better.

2) Beta

It is a measure of volatility of a security or portfolio compared to the market as a whole. Conservative investors who wish to preserve capital should focus on securities and fund portfolios with low betas while investors willing to take on more risk in search of higher returns should look for high beta investments.

3) R-squared

It is a statistical measure that represents the percentage of a fund portfolio. Mutual fund investors should avoid actively managed funds with high R-squared ratios, which are generally criticized by analysts as being "closet" index funds.