How the mighty have fallen.

Not so long ago, General Electric Co. (GE) was admired for its stellar management and financial success; it once had the highest market value of any U.S. corporation.

But after years of mediocre performance, GE has suffered a precipitous decline. Last year, GE shares were trading at about $28. Now, after a string of negative reports, the stock has fallen to below $15.

Like many leaders watching from the sidelines, I've been wondering: What the heck happened?

A report in The Wall Street Journal reveals that GE suffered from significant leadership weaknesses that made the company look good on the surface, but masked deep cracks. The good news is that we can learn from those mistakes to become better leaders in our own organizations. Here are three important lessons:

1. Create a culture in which people work together (not against one another).

The Journal article focuses on mistakes made by recently retired CEO Jeffrey Immelt. But there's a strong case to be made that the problems began with his predecessor, Jack Welch. While it's true that Welch presided over a period of unprecedented growth, he also created a dog-eat-dog culture.

Writes Simon Sinek in Leaders Eat Last: "The personality and values of the person at the top set the tone of the culture. A man who has penned five books about leadership and put his own face on the cover of all them, Welch, it's fair to say, liked his celebrity . . . and the culture of his company followed. In Jack Welch's GE, people were pitted against each other. They were driven to do whatever they could to make themselves look good . . . Being number one was all that mattered."

The problem with this approach is that it encourages jockeying for position and backstabbing--not the long-term cooperation and mutually support that builds long-term strength.

The lesson, of course, is to create a culture of "strong character," as Sinek describes it. "A company of strong character . . . will promote treating all people well, not just the ones who pay them or earn them money in the moment. In a culture of strong character, the people inside the company will feel protected by their leaders and feel that their colleagues have their backs."

2. Be realistic and supportive.

Immelt claims that he continued to promote a culture of "debate and external competitiveness." But people who worked there say that there was just as much competitiveness inside the walls of GE, and that, to be successful, you could never let anyone see you sweat. The Journal quotes Sandra Davis, who knows several GE executives as the founder of MDA Leadership Consulting: "GE itself has never been a culture where people can say, 'I can't.' "

The result was that people were not encouraged to surface issues because they were afraid to appear weak. So problems--that could be solved by working together--festered and grew.

The lesson is to encourage everyone to share everything--even when it may seem to you like people are whining.

3. Relentlessly seek the whole truth.

The problem with being a leader is that people want to please you, so they don't want to share challenges. And Immelt, reports the Journal, "didn't like hearing bad news, said several executives who worked with him, and didn't like delivering bad news, either. He wanted people to make their sales and financial targets and thought he could make the numbers, too, they said."

The lesson is to actively listen to every aspect of what's going on. Ask probing questions to get to the bottom of issues. Praise people who bring you problems. Don't rest until you hear the entire truth.

Sinek writes that a key responsibility of leaders is to create "a circle of safety" around the organization in which employees feel secure enough to do their best work. "The more we trust that the people to the left of us and the people to the right of us have our backs, the better equipped we are to face that constant threats from the outside together."