Shares of Gartner (IT) - Get Report  slumped double digits on Tuesday after the research and advisory firm reported second-quarter results that missed analysts' forecasts and lowered its outlook for the full year.

The stock recently was trading down 19% at $138.46 on the New York Stock Exchange.

The company's net income more than doubled to $103.4 million, or $1.13 a share, from $46.3 million, or 50 cents, in the year-earlier period. Analysts polled by FactSet had been estimating $1.18 a share.

Revenue came in at $1.1 billion, in line with analysts' forecasts.

The Stamford, Conn., company lowered its guidance for the rest of the year. Gartner now expects net of $190 million to $213 million, or adjusted per-share earnings of between $3.39 and $3.64, on revenue of $4.22 billion to $4.26 billion.

Analysts polled by FactSet had been expecting full-year earnings of $3.95 a share and revenue of $4.3 billion.

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