Are celebrities the new activist investors?

Taylor Swift
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Taylor Swift

Celebrities are taking cues from activist investors on Wall Street and penning letters to summon change.

Take Taylor Swift. The pop culture icon, following the strategies of Apple activist Carl Icahn and others, posted an open letter titled "To Apple, Love Taylor" on her Tumblr page Sunday asking the tech giant to change its policy on artist royalties.

Apple wasn't planning to pay musicians during its three-month free trial of Apple Music, but Swift argued the company should pay the artists, producers and writers during that period. Not compensating them, she wrote, would be "shocking, disappointing and completely unlike this historically progressive and generous company."

Within one day Apple announced it would change its policy.

Swift move, right?

Swift, who has won numerous awards for her chart-topping hits, is not a Wall Street heavyweight, nor is she a Silicon Valley insider. She does, however, have close to 60 million Twitter followers and is ranked No. 64 on Forbes 2015 "100 Most Powerful Women" list. She also has cumulative album sales (including studio efforts, live sets, EPs, etc.) topping $27 million as of March 2015, according to Billboard.com. And maybe that is enough clout in this day and age to make a difference and be heard.

Motley Crue's Nikki Sixx: Apple did the right thing
Motley Crue's Nikki Sixx: Apple did right thing   

Motley Crue's Nikki Sixx told CNBC's "Closing Bell" on Monday he's happy the company changed its tune.

"We've been in negotiations for about 12 days behind closed doors, trying to get this thing right," Sixx said. "When Taylor sent that open letter, it really was the final message they needed to hear to realize they were not doing the right thing."

Read MoreApple did right thing: Motley Crue's Nikki Sixx

Swift isn't alone in calling on a large corporation to make a significant change.

Actor Ryan Gosling, known for his lead roles in "The Notebook" and "Blue Valentine," wrote an open letter Monday to Costco Wholesale CEO Craig Jelinek, urging it sell only cage-free eggs.

"So many corporations are meeting public demand for more humane products and transparency in the food chain. I sincerely hope that Costco will set plans now to go completely cage-free for its eggs," he wrote.

When asked for comment, Costco responded with a statement it issued earlier this month after The Humane Society conducted an undercover investigation on the issue.

"Costco Wholesale is committed to the ethical treatment of animals. Our mission statement to this effect is contained on our website. We enforce this through testing and inspection of facilities, done by persons who are independent of the suppliers," the statement said.

Read MoreWhy Apple needed to appease Taylor Swift: Analyst

Update: Costco's statement in response to CNBC's request for comment was added to this story after it was originally published.