Siebel Systems expects its second quarter revenues to fall about $50m short of analyst expectations, blaming "unexpected delays in purchasing decisions".
Financial analysts expected Siebel to report $353m (£190m) in revenue for the quarter, which ended on 30 June. Siebel now expects revenue to be approximately $301m.
It called the results "disappointing", but did not elaborate in the statement on the specific reasons for the shortfall.
Siebel has been facing intense competition from Salesforce.com, which offers an inexpensive alternative to Siebel's customer relationship management software, and from SAP, said Joshua Greenbaum, principal analyst with research firm Enterprise Application Consulting.
"Siebel is being squeezed very, very tightly in a way that, in any market, makes it hard to be successful," he said.
Meanwhile, BMC Software also said it expected the company would fall short of expectations for its most recent quarter, which also ended 30 June.
The company expected revenue for its first financial quarter to be in the range of $318m and $328m, down from its prior forecast of $345m to $355m.
The company attributed the shortfall to "delays in customer purchasing decisions among larger accounts, primarily in the US".
PeopleSoft and Veritas Software also warned this week that they would not meet revenue expectations.
PeopleSoft said it expected second-quarter revenue to be between $655m and $665m, below analyst expectations of $689m.
Veritas also saw its stock plunge 35% and predicted its most recent quarter's revenue would be between $475m and $485m, down from the $490m and $505m it had predicted in last month.
Software executives have simply been too eager for a turnaround in the enterprise market, said analyst Greenbaum.
"Part of what's going on here is a number of software executives were a little overly optimistic in predicting what the quarter was going to look like," he said.
Robert McMillan writes for IDG News Service