160Want local news?Sign up for the Localist and stay informed Something went wrong. Please try again.subscribeCongratulations! You’re all set! SAN FRANCISCO – Gap Inc. is closing the Forth & Towne chain that was supposed to help the struggling retailer sell more clothes to older women, aborting the 18-month expansion so management can concentrate on reviving the company’s more established brands. The decision affects all 19 Forth & Towne stores, including one in the Westfield Topanga mall in Canoga Park, officials announced Monday. The store closures are expected to be completed by the end of June, jettisoning about 550 jobs and costing about $40 million. Signaling that some layoffs are likely, Gap is budgeting $7 million to cover severance payments and other benefits for former Forth & Towne workers, according to a filing with the Securities and Exchange Commission. Gap hoped to develop Forth & Towne into a specialty channel catering to women older than 35 who grew up in Gap jeans but found themselves sized out of the market in middle age. When it launched Forth & Towne, Gap estimated it only held a 3 percent share of the over-35 female market compared with an 8 percent share of women shoppers under 35. Gap had hoped to woo boomers – who are at the peak of their earnings and spending power – back with a store that combined the service of a boutique, the broad offerings of a department store – and a more forgiving fit.