Katie Holmes liked Alterna so much, she bought the company—well, a piece of it, anyway. Beginning next month, the the 34-year-old actress, will serve as spokeswoman and co-owner of the hair company. According to terms of the multiyear deal, Holmes will be featured in Alterna’s first print advertising campaign, which will roll out on the brand’s e-commerce site, launching mid-February, then to March consumer magazines. She will also provide the brand with input and insight on new produc...