Aruba Networks Inc. shares fell Friday after an analyst downgraded the stock to "Equal Weight," saying that despite strong sales, ongoing capital investments are limiting the company's ability to increase its earnings.

Shares of the company, which makes products for wireless computer networks, fell 53 cents, or 9.6 percent, to $5.01. In the past year, the stock has traded between $4.05 and $21.38.

In a client note, Lehman Brothers analyst Jeff Kvaal lowered his rating for the stock from "Overweight" and cut his price target to $7 from $10.

Kvaal thinks the company's "healthy new customer win rates across more verticals signal growing acceptance of its differentiated technology."

However, Aruba Networks' ongoing investments to keep its technology edge and expand its sales channel make a 19 percent to 20 percent operating margin "a few years away by our estimates," he said.