Underweight / overweight
We all have an ideal weight range determined by our body mass index. It turns out the same is true for our investment portfolios.
A portfolio is overweight if it contains an excess amount of a single security. If the portfolio lacks a sufficient amount of a security (mainly stocks or bonds), it is considered underweight. In an effort to maximize returns, the portfolio manager may choose to make a security over or underweight based on whether they think it will over or under perform the wider market.