News Summary: LinkedIn's outlook lets down Street

CLEARING THE HURDLE: LinkedIn Corp. delivered first-quarter results that topped analyst projections. The results released Thursday extended the online professional networking service's uninterrupted streak of pleasant surprises since LinkedIn's initial public offering two years ago.

THE LETDOWN: A disappointing forecast calling for slower earnings growth later this year overshadowed the first-quarter performance. LinkedIn won't be making quite as much money as analysts thought as the company ramps up hiring and spending on data centers while tweaking the way its shows online ads.

MARKET DEMOTION: LinkedIn's stock plunged more than 10 percent in extended trading. The shares have still more than quadrupled from their IPO price.