Today: The Department of Justice formally opposes efforts by Google (GOOG), Yahoo (YHOO) and other tech giants to release information on government requests for users' information. Also: Tesla falls, Pandora gains.

The Lead: Government says revealing NSA requests would help 'our adversaries'

In a formal response to a request from some of the nation's largest technology companies, the Department of Justice says that allowing Google, Yahoo and others to disclose requests for user information from the National Security Agency and other federal agencies "would be invaluable to our adversaries."

Silicon Valley's tech titans were accused earlier this year of allowing the NSA "direct access" to their servers, an allegation derived from government documents obtained by The Guardian and the Washington Post; the reports directly followed revelations about the NSA's Prism program that were leaked by former security contractor Edward Snowden. The companies vehemently denied the accusation, and Google petitioned the secretive Foreign Intelligence Surveillance Court for permission to release information on the number of requests it receives for user information. Yahoo, Facebook, Microsoft and LinkedIn later joined the effort.

Most of those companies, as well as others, have disclosed the total number of law-enforcement requests for user data in the only format the United States government allows: A general accounting that lumps national-security requests with police requests for information on suspected criminals and all other inquiries, reported in increments of 1,000.

"Greater transparency is needed," Google said upon filing its first formal request for additional disclosure rights.

In a filing made public Wednesday, the Department of Justice objected, telling the court, "Such information would be invaluable to our adversaries, who could thereby derive a clear picture of where the government's surveillance efforts are directed and how its surveillance activities change over time."

The filing states that the disclosures of classified information the companies seek is not covered under the First Amendment, as claimed in the companies' motions, and claims that the case is not appropriate for the Foreign Intelligence Surveillance Court, which is supposed to provide oversight for the nation's covert intelligence operations.

Google, Yahoo and Microsoft expressed displeasure with the government's stance in statements Wednesday, with Yahoo saying the inability to disclose the requests "ultimately breeds mistrust and suspicion -- both of the United States and of companies that must comply with government legal directives."

It is unknown when the court will rule in the case.

SV150 market report: Tesla turns around after video of fire, Pandora shoots higher

Wall Street slipped slightly Wednesday, the second day of a government shutdown sparked by partisan wrangling over health care and budget issues. While all three major U.S. stock indexes declined, the SV150 gained 0.1 percent as a sudden decline from Tesla Motors (TSLA) was countered by gains from Pandora Media and others.

Palo Alto-based Tesla had the steepest percentage drop of all SV150 companies Wednesday, with a severe slide occurring late in the session, after a video of a Model S on fire was widely publicized. The electric car maker was already suffering after Baird analysts downgraded the stock to "Neutral" on fears that Tesla's 2013 Wall Street gains of more than 400 percent are already taking into account future moves -- such as the launch of a planned SUV-type offering dubbed the Model X -- that may not come off without a hitch. Tesla closed Wednesday at $180.95, a decline of 6.2 percent.

Oakland-based Pandora was on the other end of the SV150 spectrum, gaining 5.3 percent to $26.89, after an announcement seemed to show no problems resulting from the launch of Apple (AAPL)'s competing service. Pandora announced Wednesday that its users had listened to 1.36 billion hours of music in September, an 18 percent year-over-year gain and consistent with August's listener numbers, while market share and the number of active listeners increased from August. The metrics were important to investors after Apple announced that 11 million people had tried out iTunes Radio, Apple's Pandora competitor that launched along with iOS 7, in the first week of availability; Pandora stock slipped mightily on the day of that announcement. Apple gained 0.3 percent to $489.56 Wednesday despite a report that suggested a retina iPad Mini couldn't be ready for the Christmas holiday season.

In between Pandora and Tesla, Silicon Valley stocks were mostly quiet. Google gained 0.1 percent to $887.99 after announcing only the second non-Google app to add Chromecast support, Hulu Plus, while facing an Israeli inquiry into its Waze acquisition. Oracle (ORCL) gained 0.5 percent to $33.58 while fighting a stockholder seeking to cause a stir about founder and CEO Larry Ellison's pay, and Netflix (NFLX) again hit record prices while closing with a 1.9 percent gain at $330.73.

The acquisition market was active Wednesday for Silicon Valley: Monsanto purchased a San Francisco software company for nearly $1 billion, Go Daddy picked up a Mountain View startup called Ronin, and San Mateo-based Pivotal purchased Xtreme Labs for $65 million.

Up: Pandora, SunPower (SPWRA), Netflix, AMD, Salesforce, Oracle, VMware, Hewlett-Packard (HPQ), Cisco (CSCO), Apple

Down: Tesla, Electronic Arts (ERTS), Adobe (ADBE), SolarCity, Gilead, eBay (EBAY), Yelp, Symantec, Zynga, Yahoo, NetApp

The SV150 index of Silicon Valley's largest tech companies: Up 1.02, or 0.08 percent, to 1,350.64

The tech-heavy Nasdaq composite index: Down 2.96, or 0.08 percent, to 3,815.02

The blue chip Dow Jones industrial average: Down 58.56, or 0.39 percent, to 15,133.14

And the widely watched Standard & Poor's 500 index: Down 1.13, or 0.07 percent, to 1,693.87

Check in weekday afternoons for the 60-Second Business Break, a summary of news from Mercury News staff writers, The Associated Press, Bloomberg News and other wire services. Contact Jeremy C. Owens at 408-920-5876; follow him at Twitter.com/jowens510.