Fast-food chains battle for low-income diners with summer value meals

Subway started phasing out its $5 footlong sandwiches a decade ago. But these days, other fast-food chains have revived the $5 price point, hoping to win over customers who have cut back their spending.As many restaurant companies prepare to report their second-quarter results, investors are expecting to hear that diners are visiting their locations less frequently and that sales have turned sluggish, with few exceptions such as Chipotle.