By midday, shares had tanked 26% to $9.62.
Trading volume of 1.4 million shares was nearly 20 times its three-month daily average.
The home audio technology developer said it intends to offer around $45 million of common stock in an underwritten public offering. The company hasn't yet priced the offering.
In a statement, Parametric said it intends to use net proceeds to "repay certain indebtedness and for working capital and other general corporate purposes."
Needham & Company will act as sole book-running manager, while Cowen and Company and Wedbush Securities will act as as co-lead managers. Lake Street Capital Markets is acting as co-manager for the offering.