Asked to name an inspiring CEO, and most of us can easily name a half dozen or more: Steve Jobs, Meg Whitman, Bill Gates, Mark Zuckerberg, Marissa Mayer. Now, name three extraordinary chief operating officers? That's another story.

Chief operating officers are oftentimes unsung heroes in a somewhat amorphous role. Accenture called the COO, “perhaps one of the least understood roles in business today.”

As the founder of a private equity crowd funding network and in my years in private equity investing, I’ve seen how vital COOs are to companies, particularly during periods of rapid growth or business transformation when execution risks are high.

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What is it that makes a great COO? With CEOs we talk about strategic vision, leadership, determination, an ability to motivate and inspire -- those traits that create iconic corporations. But the chief operating officer role is less clearly defined.

Keith Rabois, former COO of Square, describes the COO at a startup as a doctor in an emergency room, constantly fixing things, triaging and diagnosing issues to determine if they are minor or potentially fatal.

As Ernst & Young pointed out in The DNA of the COO, “Rather than possessing a single set of skills that can be easily identified in any business, COOs have to adapt, chameleon-like, to the environment in which they find themselves.”

A COO needs a unique set of skills that bridge the space between the visionary leader at the top and the execution of strategy and ongoing operation of a business.

I have found that great COOs have four attributes, which are good examples to follow for anyone in business: 

1. They are strategic with a focus on details. Sheryl Sandberg -- arguably the highest-profile COO in America today -- has an extraordinary ability to dig deep on a wide range of issues. At the same time, she knows the bounds of her responsibilities so as not to lose sight of the forest for the trees. When Facebook hit sticking points in key negotiations with PayPal, Sandberg reportedly helped smooth out differences by contacting John Donahue, CEO of PayPal’s parent company eBay.

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A successful COO balances a breadth of experience and knowledge with an ability to manage strategically. They keep their company’s high-level strategy front-and-center while understanding the details of day-to-day execution to ensure what needs to happen does happen. Handling those details can be no small matter. About six in 10 COOs say the complexity and diversity of the position is fundamentally what makes it worthwhile, according to Ernst & Young’s survey of hundreds of COOs.

2. They appreciate talent. A good COO is a people person. They understand the business depends on talented individuals working as a team. As they maintain the operations, they keep an eye out for ways to improve the company by deepening the pipeline of talent, constantly raising the level of talent through strong hires, and providing opportunities to develop existing team member skills.

3. They have no ego: The best COOs put the organization first. There is a total lack of ego. These COOs find ways time and again to highlight others. They will decline speaking engagements and instead give those opportunities to a business-line head or head of marketing. Similarly, when media outlets request interviews, the top COOs will find ways to share the limelight with others.

4. They are data driven: Sometimes it is tempting to rely on your gut for decisions in business. But when a CEO or a business-line head, or director of procurement says, “I just know this initiative will be a home run,” the effective COO is the one who will stop them or slow them down and ask for data to guide decisions. Because they are responsible ensuring strategic vision translates into profitable operations, COOs must be data-driven. Rather than allow the business to be guided by instincts, internal politics, hunches, or executives’ gut feelings, the best COOs will insist the business be driven by data.

Businesses should not underestimate the value of a strong COO. Not only are good COOs instrumental in turning strategy into operational and financial success, the COO role is the most common stepping stone by far to the CEO seat.

Forty-four percent of Fortune 500 and S&P 500 CEOs had been COOs, according to the Crist Kolder Assoicates 2013 Volatility Report. Stellar COOs move up -- look no further than Tim Cook at Apple, and the recent reports that Sandberg is a contender to succeed Bob Iger as CEO of Disney.

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