Holding the title of chief operating officer ain't what it used to be.

The job commonly viewed as one step away from the CEO role is slowly turning into a dying breed, the lastest evidence of which surfaced Friday when Twitter COO Ali Rowghani abruptly resigned.

U.S. companies have been gradualy eliminating the position for more than a decade, The Wall Street Journal reports. The share of Fortune 500 and S&P 500 companies with a COO fell from nearly 50 percent in 2000 to 35 percent in 2013. In the healthcare and industrial sector the title is particularly rare, with just one out of four businesses appointing an operating chief.

The COO post "just seems to me kind of an antiquated position," David Larcker, a professor of corporate governance at Stanford, tells WSJ. During just the past six months, companies including McDonald's, Tiffany & Co. and Yahoo have all done away with the COO role. Filling the void left by COOs are specialists including risk and information experts or financial gurus, the report said. 

So does your company need a COO? The answer varies depending on the industry. Slighly more than half of all service businesses from the Fortune and S&P sample reported having a COO in 2013, while the percentage of technology and consumer companies with a COO hovered at around 35 percent last year.

Still, COOs continue to play a vital role at many of the U.S.'s most successful companies. Facebook COO Sheryl Sandberg is reportedly the highest-paid COO at the company, and last December, photo-sharing app SnapChat wooed former Facebook and Instagram executive Emily White to be its COO.

Is having a COO crucial for your business? Let us know in the comments.