Today: A tech renaissance on Wall Street pushes the Standard & Poor's 500 to more record levels and several Silicon Valley companies to 52-week highs. Also: Personal computer sales dip the most in nearly two decades.

New 52-week highs across valley help push indexes to new records

While the Dow Jones and Standard & Poor's 500 have sprung to records in 2013, technology companies have not been as successful on Wall Street, with Apple's (AAPL) fall keeping the SV150 index of Silicon Valley's largest tech firms in negative territory for the year and the Nasdaq trailing the gains of its brethren indexes by a wide margin. The last two days have changed that dynamic, however, with valley stocks such as Yahoo (YHOO), eBay (EBAY) and Gilead pushing to new 52-week highs and helping, instead of hindering, index records.

In Wednesday trading, the S&P 500 finally broke through its record intraday high set in 2007, which had been a barrier despite the index's record closing numbers of the past two weeks, a record broken again Wednesday with a 1.2 percent increase. The Dow Jones industrial average also established new intraday and closing highs as it gained 0.9 percent.

The Dow and S&P daily increases paled in comparison to the Nasdaq, however, as the tech-heavy index drove 1.8 percent higher, the same percentage gain as the S&P's tech components, which led that index's 10 sectors. The SV150 soared even higher, adding 2 percent on the day as several valley companies reached 52-week highs.

Yahoo was one of those companies, again reaching prices not experienced since 2008. In fact, MarketWatch pointed out that Yahoo reached the same price at which it sat on the day Microsoft walked away from merger talks with the Sunnyvale Internet company nearly 5 years ago.

"Yahoo was written off for dead, destined to trade in the teens forever. It's a remarkable turnaround," Yahoo investor and Ironside Capitol founder Eric Jackson told MarketWatch.

CEO Marissa Mayer has led the resurgence by focusing on small mobile acquisitions meant to build the company's talent base, with most of those efforts led by Jacqueline Reses, who received the new title of chief development officer this week, according to a Bloomberg News profile. The stock advanced 1.6 percent to $24.20 Wednesday and moved as high as $24.32 after reports that Yahoo was meeting with Apple on a partnership that would place more of its mobile apps on the Cupertino company's popular devices.

EBay, which had a very strong 2012, reached a new 52-week high as well on Wednesday after an executive for the San Jose e-commerce giant announced at a conference that it was getting into targeted ads, challenging rival Amazon at a game it helped start. Shares moved as high as $57.58 before closing at $57.30, a daily increase of 2.2 percent.

Gilead, which has been on a tear since announcing Monday that it would put its hepatitis C drug up for FDA approval, also established a new high; the Foster City biotech company sold for as much as $49.85 and closed with a 3 percent advance at $49.73. San Jose software giant Adobe (ADBE) also established a new 52-week high Wednesday, reaching as high as $45.40 before closing with a 1.2 percent gain at $44.70. Two companies that debuted in 2012 reached record highs Wednesday, with SolarCity moving 1.6 percent higher to $20.46 and San Francisco big-data outfit Splunk advancing 1.8 percent to $41.16.

San Jose networking giant Cisco (CSCO) came close to its 52-week high of $21.98 before closing with a 2.4 percent gain at $21.47, but Sunnyvale rival Juniper Networks had a better day with a 4.7 percent gain to $18.84. Facebook overcame so-so reviews of its new Home app for Android devices and advanced 3.7 percent to $27.57, and other social-networking stocks followed suit: LinkedIn gained 3.1 percent to $177.31, Yelp advanced 4.6 percent to $25.75, and Zynga increased 1.8 percent to $3.45.

Even Apple managed a solid gain Wednesday, gaining 2 percent to $435.69, its highest closing price of April. With its market capitalization back up to $409.1 billion, the Cupertino tech titan is again the most valuable company in the United States.

PC sales suffer massive dip in first quarter

Thursday's trading may not be as strong for technology companies, however, especially those that specialize in personal computers. After trading ended Wednesday, two analysis firms that track PC sales announced that they declined by the most in recent memory despite the debut of Microsoft's Windows 8 operating system.

IDC reported that sales in the first quarter of 2013 declined 13.9 percent from the same quarter in 2012, nearly double the drop it expected and the worst the company has seen in nearly two decades of tracking the industry. Gartner reported a slightly smaller but just as devastating drop of 11.2 percent.

The results are especially tough for Palo Alto's Hewlett-Packard (HPQ), the No. 1 personal-computer manufacturer in the world. IDC recorded a year-over-year drop of more than 23 percent in global shipments for the company, which mirrored Gartner's report of a 23.6 percent drop from the first quarter of 2012. HP barely maintained its lead as the top PC manufacturer according to Gartner's numbers, with 14.8 percent of the market to Lenovo's 14.7 percent.

IDC specifically pointed a finger at Microsoft for the numbers, blaming its Windows 8 operating system not just for failing to help the PC market, but for actually harming it.

"At this point, unfortunately, it seems clear that the Windows 8 launch not only failed to provide a positive boost to the PC market, but appears to have slowed the market," IDC's Bob O'Donnell said in Wednesday's announcement, later adding, "Microsoft will have to make some very tough decisions moving forward if it wants to help reinvigorate the PC market."

Microsoft gained 2.3 percent to $30.28 in regular trading Wednesday, but fell more than 1.6 percent in late trading; HP advanced 0.5 percent to $22.32 in the main trading session, but fell more than 2.4 percent in after-hours action.

Silicon Valley tech stocks

Up: Ruckus, Juniper, Yelp, Applied Materials, Facebook, Tesla, Palo Alto Networks, LinkedIn, Gilead, Cisco, Intel (INTC), eBay, Oracle (ORCL), Apple, Electronic Arts (ERTS), Zynga, Splunk, Google (GOOG), Intuit (INTU), VMware, SolarCitry, Nvidia, Yahoo, Adobe

Down: SunPower (SPWRA), Netflix (NFLX), NetApp, Advanced Micro Devices

The tech-heavy Nasdaq composite index: Up 59.39, or 1.83 percent, to 3,297.25

The blue chip Dow Jones industrial average: Up 128.78, or 0.88 percent, to 14,802.24

And the widely watched Standard & Poor's 500 index: Up 19.12, or 1.22 percent, to 1,587.73

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/mercbizbreak.