Dec 26 (Reuters) - The following are the top stories in the Wall Street Journal. Reuters has not verified these stories and does not vouch for their accuracy.

* The Obama administration is increasingly concerned about a wave of digital extortion copycats in the aftermath of the cyberattack on Sony Pictures Entertainment, as the government and companies try to navigate unfamiliar territory to fortify defenses against further breaches. (http://on.wsj.com/1zltw1I)

* China's central bank is taking more steps to boost banks' lending abilities in an effort to shore up the world's second-largest economy, according to banking executives with knowledge of the matter. (http://on.wsj.com/142WJqi)

* Officials at the Centers of Medicare and Medicaid Services are looking for ways to reduce fraud and abuse without restricting access to medical care. (http://on.wsj.com/1xiKZcR)

* Standard & Poor's Ratings Services is nearing a settlement with regulators over their investigation of how the company graded real-estate bonds, according to people familiar with the matter. (http://on.wsj.com/1zX9woM)

* About 300 small, niche theaters are showing the movie "The Interview," which was yanked by Sony last week after big theater chains refused to show it due to a terrorist threat. (http://on.wsj.com/1APnCdq)

* RadioShack Corp has shut more stores in the past two months than the rest of the year, though it's hard to tell the difference. The chain still has a heavy surplus of stores in many local markets. (http://on.wsj.com/1EmMtZV)

* Sumitomo Mitsui Financial Group Inc said it would purchase Citigroup Inc's Japanese retail operations, leaving the New York bank to focus on corporate banking, investment banking and other institutional businesses in the world's third-largest economy. (http://on.wsj.com/1AaI9cs) (Compiled by Supriya Kurane in Bengaluru)