TORONTO, Canada — Aritzia Inc., a Canadian women's fashion retailer, may raise as much as C$400 million ($304 million) in its initial public offering after boosting the amount of shares being offered by 25 percent.Aritzia owners lifted the number of subordinated shares being sold to 25 million from 20 million, according to Friday sale documents. The shares are being marketed for C$14 to C$16 each, and pricing is set for September 26.Aritzia was started in Vancouver in 1984 by Brian Hill, a third-generation retailer and current chief executive officer. Berkshire Partners, a Boston-based private equity firm, bought a majority share in the retailer for an undisclosed sum in 2005. Aritzia, which sells clothes and accessories aimed at women aged 15 to 45, has 75 retail locations across North America, including New York, Toronto, Montreal, Boston, Chicago and San Francisco, according to its regulatory filing.Canadian Imperial Bank of Commerce, Bank of America Corp.’s Merrill Lynch Canada unit and Toronto-Dominion Bank are leading the sale. Aritzia, will trade on the Toronto Stock Exchange under the ticker symbol ATZ after the transaction closes.By Doug Alexander; Editors: Peter Eichenbaum, David Scanlan, Jacqueline Thorpe, Steven Frank.