By Rex Crum, MarketWatch

SAN FRANCISCO (MarketWatch) -- Google Inc. gained ground Wednesday after the tech giant kicked off its annual developers conference, and Zulily Inc. surged following a rating upgrade to lead a broad slate of gains for the tech sector.

Google (GOOGL) rose 2.3% to close at $585.93 a share after the company held the keynote presentation at its I/O developers conference in San Francisco. Among the highlights were the debut of smartwatches from LG and Samsung that run on Google's Android operating system, and Android TV, a software platform that can be used to watch and organize TV programs and streaming-video apps from the Internet.

Google said the first set-top boxes to support Android TV will be available in the fall.

Zulily (ZU) climbed more than 9% to close at $39.88 a share after Goldman Sachs analyst Debra Schwartz raised her rating on the online clothing retailer to buy from neutral. Schwartz also raised her price target on Zulily's stock to $50 a share from $47. "We see a good entry point as the company expands its merchandising, fulfillment, and marketing initiatives which we expect to drive higher-than-expected customer growth into 2015."

Among other leading tech stocks, gains came from Apple Inc. (AAPL), Microsoft Corp. (MSFT), Facebook Inc. (FB), Netflix Inc. (NFLX) and Intel Corp. (INTC)

More gains came from Facebook Inc. (FB), Broadcom Corp. (BRCM) and Pandora Media Inc. (P).

Investors await the pricing of digital camera company GoPro Inc., which was scheduled to set the price of its IPO prior to trading as a public company on Thursday.

The tech-heavy Nasdaq Composite Index (RIXF) shook off its early weaknesses to rise 29 points and close at 4,379, while the Philadelphia Semiconductor Index (SOX) also eked out a small gain.

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