By Nicola Leske and Olivia Oran

NEW YORK (Reuters) - Data storage company Box, one of Silicon Valley's highly anticipated IPO candidates, has selected Morgan Stanley, Credit Suisse and JPMorgan Chase & Co to lead a proposed initial public offering, according to three people familiar with the matter.

The fast-growing technology start-up's IPO could come in the first half of 2014 and raise about $500 million, the people said.

Box, started in 2005 by University of Southern California drop-out Aaron Levie and his childhood friend, Dylan Smith, is an online storage company that provides users with free storage, but charges fees for additional space.

Representatives for Box, Morgan Stanley and Credit Suisse did not immediately respond to requests for comment. JPMorgan declined to comment.

Los Altos, California-based Box is one of several high-profile start-ups gearing up for an IPO, on the heels of a successful debut by Twitter Inc on Thursday, which raised more than $1.8 billion for the microblogging company.

Other closely watched startups which may be exploring an IPO include mobile payments company Square, Uber and Pinterest.

The deal is a big win for Morgan Stanley, who was passed over for the leading role in Twitter's IPO in favor of Goldman Sachs Group Inc, despite being known for its tech franchise led by banker Michael Grimes.

Grimes' team led high profile technology offerings such as Facebook , LinkedIn Corp, Zynga Inc and Pandora Media Inc.

Morgan Stanley lags behind Goldman Sachs as the No. 2 underwriter for U.S. listed technology IPOs so far this year, according to Thomson Reuters data. The bank still led a greater number of deals for larger technology companies including software firm Veeva Systems Inc, security company FireEye Inc and online coupon company RetailMeNot.

A public float for Box would come amid the strongest dollar volume for U.S. IPOs since 2000.

U.S. companies have raised $50.7 billion in proceeds year to date, a 26 percent increase compared to a year earlier, according to Thomson Reuters data.

This year is also the strongest year for the number of U.S. new listings since 2004.

Box has been valued at more than $1.2 billion by private investors, according to 2012 venture rounds, although it remains unclear whether the company is profitable.

The online storage company has tapped into growing demand by professional workers who increasingly want to share documents across different computers. IT has been locked in fierce competition with a number of rivals, including Dropbox, another privately held firm that is valued at $4 billion.