“It’s a challenge, because a lot of the ones who are very successful at it are making a lot of money, which in all honesty can be hard to match with the traditional publishing royalty structure,” said Leah Hultenschmidt, the Forever editor who acquired the Hacker series from Ms. Wild.

Publishers fighting to recruit top-selling authors have other reasons to be alarmed by the growth of self-publishing. As independent authors grab a bigger slice of the e-book market, digital sales by traditional publishers fell by 11 percent in the first nine months of 2015, according to data gathered from more than 1,200 publishers by the Association of American Publishers.

Last year, a third of the 100 best-selling Kindle books were self-published titles on average each week, an Amazon representative said. Some analysts attribute the dip in publishers’ e-book revenue in part to the glut of cheap self-published books, which often sell for as little as $1.

Independent authors are now moving beyond e-books and making inroads into the physical retail market. A handful of the top-selling self-published authors, among them Ms. Wild, Barbara Freethy, H.M. Ward, C J Lyons and Bella Andre, have struck distribution deals with Ingram Content Group, a major book printer and distributor, allowing them to sell their novels in bookstore chains, big-box stores and airports. Thirty-six percent of book buyers read only print books, according to a 2015 survey conducted by the Codex Group.

“I can sell my books exactly as if I was Random House or Simon & Schuster,” said Ms. Freethy, who started self-publishing romance novels in 2011 and said she had sold more than five million copies. “There’s been no pushback from booksellers.”

With all the tools of a publisher at their disposal, it’s no surprise that a few of the most ambitious authors — among them the paranormal suspense writer J.R. Rain and the mystery writer Gemma Halliday — are forming their own imprints and recruiting other writers. The business models for author-led imprints vary, but most of them buy publication rights to the books and take a cut of royalties in exchange for editing, formatting, packaging and marketing the books, much like a traditional publisher. Some offer a modest advance. The biggest draw for struggling authors, though, is the chance to be associated with a more successful author’s brand.

After selling three million copies of her own books, Liliana Hart, a high school band teacher turned mystery writer, started her own imprint, SilverHart last year and acquired works by four other authors.