NetScout executives said the company now expects to earn between 1 cent and 3 cents a share in its fourth quarter on sales between $20 million and $22 million, down 41 percent from the third quarter.
First Call consensus was projecting a profit of 14 cents a share in the quarter.
NetScout, which develops infrastructure management software, blamed the shortfall on "sudden, broadening constraints" on technology spending that have delayed orders and lengthened sales cycles.
"Even though we continue to see a strong flow of very good opportunities and interest in the value provided by our products, it has become extremely difficult to reliably forecast in this tough economic environment," said Chief Executive Officer Anil Singhal in a release.
The company expects sequential quarterly sales growth of between 10 percent and 12 percent for the next four quarters.
On Wednesday, Janney Montgomery Scott analyst Richard Sherman downgraded the stock from a "buy" rating to "accumulate" and set a 12-month price target of $8 a share.
Last quarter, NetScout earned $5.2 million, or 17 cents a share, on sales of $37.5 million.
NetScout shares moved up to a 52-week high of $25.56 in October before falling to a low of $4.50 a share earlier this month.
Five of the six analysts tracking the stock maintain either a "buy" or "strong buy" recommendation.