Kleiner Perkins Caufield & Byers has agreed to invest in the fast-growing ephemeral message service Snapchat Inc. at a valuation of close to $10 billion, people with knowledge of the matter said.

Snapchat, which has talked to several potential investors in recent months, is in the process of raising a large investment round that would make it one of the world's most valuable private tech startups despite virtually no revenue.

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