$3.5 trillion so far, and more ahead for buybacks

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The high likelihood that the Federal Reserve will maintain current interest rate policy means stock buybacks likely will remain in vogue.

Just a short time ago, it looked like the dividend payments and share repurchase programs that companies have used aggressively to boost their stock prices might start to fade once the U.S. central bank unwound its stimulus and ultimately normalize interest rates.

That's because companies have used cheap financing courtesy of the Fed as a means to underwrite those buybacks. Nonfinancial companies have a post-crisis high debt of $13.1 trillion on their balance sheets, compared to $1.8 trillion of cash that they've been hanging onto.

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After central bank officials did some gentle saber rattling this summer about pulling back, or tapering, its $85 billion in monthly bond-buying, interest rates spiked higher.

Companies, in turn, decreased their buybacks in July and August making the third quarter the lowest of the year at $168.9 billion, according to Birinyi Associates.

But that turned around in September as companies authorized $68.1 billion in buybacks amid easing fears over rates. With the Fed now thought to be on hold until at least March, the coast looks clear for buybacks.

"Even though interest rates have increased over the last few months, debt financing is still cheap by historical standards, especially when compared to equity financing," Citigroup strategists said in a note. "Given the large cash piles on company balance sheets, we think companies will continue to return capital to shareholders via buybacks."

(Read more: John Sculley to Apple: Ignore Carl Icahn's advice)

Activist investor Carl Icahn made headlines in the past few days after demanding that Apple launch a $150 billion buyback, after the tech giant took back $16 billion earlier this year. In related news, insurance broker Aon revealed a larger-than-expected $500 million buyback. in the third quarter.

(Read more: Icahn to Apple: I want a $150 billion buyback)

Citigroup's proprietary screen for the top buyback companies has returned an average 13.6 percent a year over the past 13 years and is up 36 percent in 2013. Companies are believed to have spent $3.5 trillion on buybacks during the period, according to a University of Massachusetts Lowell analysis.

For its measure, Citi considers companies that have reduced share count by 5 percent over the past year and picks the largest 50 companies that fall into that category.

The top five U.S. companies that currently meet the criteria are Seagate Technology,DirectTV, CNBC parent Comcast, O'Reilly Automotive and Pfizer.

Consumer discretionary stocks are the most represented in the group, followed by healthcare, financials and information technology.

—By CNBC's Jeff Cox. Follow him on Twitter @JeffCoxCNBCcom.