Amazon.com Inc. will acquire comiXology, an e-retailer of digital editions of comic books. Amazon and comiXology did not disclose terms but a letter posted by comiXology co-founder and CEO David Steinberger on comiXology.com says the e-retailer will continue to operate as a subsidiary of Amazon.com.

The companies expect to close the deal by the end of June. “We look forward to investing in the business, growing the team, and together, bringing comics and graphic novels to even more readers,” says David Naggar, vice president, content acquisition and independent publishing, at Amazon.

Customers of comiXology.com access their comic books via the web or through apps available on devices running iOS, Android or Windows 8 operating systems. It also has an app for the Amazon Kindle Fire tablet. ComiXology.com launched in 2007 and appeared on Internet Retailer’s Hot100 list as one of the most innovative e-retail sites of 2013. ComiXology says its iPad app was the top-grossing non-game iPad app in 2012 and 2013.

Amazon.com is No. 1 in Internet Retailer’s Top 500 Guide. Last year, Amazon acquired TenMarks Education Inc., a service that develops customized lesson plans and tutoring in math for students and is accessible via Kindle Fire tablets, and Goodreads.com, a social network for book recommendations.