|1.||weighing less than is average, expected, or healthy|
|a. having a lower proportion of one's investments in a particular sector of the market than the size of that sector relative to the total market would suggest|
|b. (of a fund etc) disproportionately invested in this way: pension funds have become underweight of equities|
underweight un·der·weight (ŭn'dər-wāt')
Weighing less than is normal, healthy, or required. n.
Insufficiency of weight.