By Rex Crum, MarketWatch

SAN FRANCISCO (MarketWatch) -- Tech stocks put in a mixed trading performance Wednesday, with Google Inc. rising ahead of its annual developers conference and online retailer Zulily Inc. surging following a ratings upgrade from brokerage Goldman Sachs.

Google (GOOGL) rose $4.17 a share to $576.56 as the company prepared for its I/O developers conference in San Francisco. Google is expected to highlight developments with its Android operating system and may unveil some of the first smartwatches that operate on Android.

Zulily (ZU) climbed more than 9% to $39.90 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."

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

Decliners included Apple Inc. (AAPL), Microsoft Corp. (MSFT), Netflix Inc. (NFLX) and Yahoo Inc. (YHOO).

The tech-heavy Nasdaq Composite Index (RIXF) rose 3.5 points to 4,353, while the Philadelphia Semiconductor Index (SOX) dipped into the red.

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