Short Market Value

What Does Short Market Value Mean?
The total value of all short sales in place in a customer's account at the end of the trading day. 

Investopedia explains Short Market Value
The short market value of an account is taken into consideration when determining whether a customer has met the margin requirement on a brokerage account. If the account has both a short market position and a long market position, both margin requirements must be met individually, or the account may be restricted until the margin requirement is met.