* 1st-quarter adj earnings $0.24/share vs est $0.21
* Expects 2nd-quarter adj profit $0.22-$0.26/share vs est $0.27
* Expects 2nd-quarter revenue $1.07-$1.11 bln vs est $1.11 bln
* Shares fall 5 pct after hours
April 23 Network equipment maker Juniper Networks Inc forecast a second-quarter profit below analyst expectations due to weak spending by the U.S. government and the financial services industry, sending its shares down more than 5 percent in after-hours trading.
Federal spending on everything from defense to schools has been slashed due to automatic spending cuts that came into effect in March after Congress failed to find an alternative plan to reduce spending.
Juniper rival F5 Networks Inc forecast second-quarter results earlier this month that were way below analysts' expectations, hurt partly by the sequester as well as by a slowdown in orders in North America.
Juniper's first-quarter profit came in modestly ahead of market estimates on improved demand from telecom providers.
However, Mizuho Securities USA analyst Joanna Makris said the service provider business remained a big challenge.
"We're not seeing a seasonal increase in carrier capex," she said.
Juniper, whose competitors also include Cisco Systems Inc , said it expects a second-quarter profit of 22-26 cents per share, excluding items, on revenue of $1.07-$1.11 billion.
Analysts had expected an adjusted profit of 27 cents per share and revenue of $1.11 billion, according to Thomson Reuters I/B/E/S.
Juniper's routing business is also weakening, hurt by mass availability of routers and intensifying competition from companies such as Alcatel Lucent SA.
"Juniper is facing a number of key issues including lack of compelling enterprise products, share loss in edge routing and a core routing market that is no longer growing," analysts at MKM Partners said in a pre-earnings note.
The company's net profit rose to $91.0 million, or 18 cents per share, in the first quarter, from $16.3 million, or 3 cents per share, a year earlier.
Excluding items, it earned 24 cents per share, beating the average analyst estimate of 21 cents per share.
Revenue rose 3 percent to $1.06 billion, in line with estimates.
Juniper's shares, which have lost a fifth of their value since the company reported fourth-quarter results on Jan. 24, fell to $16.40 in extended trading after closing at $17.36 on the New York Stock Exchange on Tuesday.