Party City Holdings Inc., a vertically integrated provider of decorated party supplies with roughly 800 locations in the US, filed on Friday with the SEC to raise up to $350 million in an initial public offering. The Elmsford, NY-based company, which was founded in 1947 and booked $1.6 billion in sales last year, was acquired by private equity firms Berkshire Partners (36% pre-IPO stake) and Weston Presidio (17%) in April 2004. Principal shareholder Advent International (37%) entered in August 2008. Party City plans to list under the symbol PRTY. Goldman, Sachs & Co., BofA Merrill Lynch, Barclays Capital and Deutsche Bank Securities are the lead underwriters on the deal, for which pricing terms and timing were not disclosed.