Shares of QLogic Corp. plummeted after Aliso Viejo-based networking-equipment maker was downgraded by two investment banks.

Investors sent shares down more than 18% in midday trading, to a market value of about $997, after Stifel Nicolaus Weisel and Morgan Stanley & Co. LLC and ThinkEquity LLC downgraded the company.

Both investment banks cut their rating on QLogic from “buy” to “hold.”

The downgrades came a day after QLogic reported adjusted profits in the June quarter that narrowly missed Wall Street expectations. The company’s revenue fell in line with estimates.

The company had a $25.3 million in profits, down 39% from a year earlier.

Analyst on average had forecast profits of $26.3 million.

Revenue came in at $130 million, down 9.8% from a year ago, and in line with Wall Street expectations.

Analysts are forecasting profits of $29.2 million on about $139 million in sales for the current quarter.

QLogic makes electronics such as switches and adapter cards that speed up the flow of data on corporate storage networks.