When investors are happy to see the boss go

On August 28, the company's shares gained 4.1% to $59.75 on news Braly was resigning (She was one of 20 women running Fortune 500 companies). During her five-year tenure, investors grumbled as WellPoint missed earnings estimates and cut its forecast twice in four months. Even before Braly's departure, investors had reportedly been touting other candidates to head the company.

Braly is not alone, however. Over the years investors have greeted plenty of departing CEOs with a cheer. Here's a look back at the most memorable.

Barclays CEO Robert Diamond

After this British bank admitted to rigging costs charged when banks lend each other money, it was almost expected that that someone high up would have to go.

CEO Robert Diamond stepped down July 3, 2012 following the resignations of other executives embroiled in the interest rates scandal. A week prior, the London-based bank, among the world's largest, was fined more than $450 million by British and U.S. regulators for under-reporting its interest rates as part of the London Interbank Offered Rate. The rate, set in London each trading morning, not only influences of the costs banks pay each other for loans but it also influences the broader market and what typical consumers pay for everything from home mortgages to credit cards.

Markets, stunned by corruption at the bank, cheered at Diamond's departure. Barclay's stock gained as much as 4.8% the day of his resignation. This was a welcome boost, given that shares plunged 16% on June 28 on speculation the bank could face billions of dollars in lawsuits.

Nomura Securities CEO Kenichi Watanabe

In the wake of an insider trading scandal, the CEO of this Japanese conglomerate resigned after four years leading the firm.

Japanese regulators were investigating Nomura for leaking information to clients ahead of planned securities offerings by energy company Inpex, Mizuho Financial Group and Tokyo Electric Power in 2010. Nomura had admitted that some employees were involved in leaking inside information.

Kenichi Watanabe announced his departure on July 26, after other executives stepped down. And markets reveled on the news that day, rising 5.7% after falling by a third since reports of the investigation surfaced four months prior.

Best Buy CEO Brian Dunn

The head of Best Buy had been sitting in the doghouse with investors, as he world's largest electronics retailer struggled to keep up with the hyper-competitive world of online shopping.

CEO Brian Dunn, who rose from sales associate to lead Best Buy over the course of 28 years, resigned in April 2012 after the board began investigating his personal relationship with an employee. Judging by investors' reactions, it appeared they cheered the news but were well aware the big-box retailer face big challenges in the months going forward. Shares rose 3.3% on news before quickly falling 2.3%. Now Best Buy founder and former chairman Richard Schulze is attempting to acquire the struggling retailer.

Starwood CEO Steven Heyer

Investors of the Stamford, CT-based lodging giant that owns various upscale hotel brands including Westin and Sheraton appeared relieved when Starwood CEO Steven Heyer quit in 2007.

The problem wasn't so much that business at Starwood was doing badly. At the time, the U.S. hotel industry was booming from a rising number of business travelers. Starwood's board of directors, however, didn't agree with Heyer's management style and lost confidence in his leadership.

Shares of Starwood rose 4.6% on April 2, 2007 on news of his departure, closing at $67.82. Investors not only saw it as a positive management change, but also as increasing the chances of a buyout. At the time, the firm had low debt and strong cash flow, making it frequently mentioned as a buyout target.

Yahoo CEO Carol Bartz

Investors seemed to have breathed a sigh of relief when the struggling Sunnyvale, CA-based internet company infamously fired CEO Carol Bartz -- over the telephone.

Bartz stepped down from Yahoo's board on Sept. 9, after being fired by three days earlier by Chairman Roy Bostock. This led her to accuse the board of mistreatment, telling Fortune's Patricia Sellers, "These people fucked me over."

Investors overlooked that, however. Over the three-day period between when Bartz was fired as CEO and the time she resigned from the board, Yahoo's shares climbed more than 10%.

Merrill Lynch CEO Stan O'Neal

Investors applauded the first Wall Street chief executive forced out for overlooking the extent of the 2007 credit-market crunch and subsequent financial crisis.

Shares of Merrill Lynch climbed 8.5% to $66.09 in New York trading on Oct. 26, 2007 on speculation that Stan O'Neal would leave. O'Neal lost the confidence of investors after the bank posted a whopping $2.24 billion loss, and he resigned several days later.

Though investors might have been happy that he was gone, O'Neal may have walked away just as pleased. His compensation package was valued at $161.5 million.

Hewlett-Packard CEO Leo Apotheker

Léo Apotheker had been CEO of troubled PC manufacturer Hewlett-Packard for less than a year when investors in 2011 were already calling for new leadership. Apotheker had replaced Mark Hurd, who abruptly resigned as HP CEO after the company found that he submitted false expense reports to hide a personal relationship with a contractor.

Apotheker had been a surprise replacement -- not just because the company had been widely expected to appoint an internal employee, but he came with a questionable past, having been ousted from the top spot at SAP in 2009.

Reports on September 21 that the board was considering firing Apotheker and replacing him with former eBay CEO Meg Whitman sent HP shares soaring 7%. The next day, HP announced just that.

UBS CEO Oswald J. Grübel

Big losses from a rogue trading scandal brought down UBS CEO Oswald J. Grübel in 2011. The Swiss bank reported a $2.3 billion loss after a mid-level employee made unauthorized trades under Grübel's watch.

Amid his departure, Grubel had said the scandal had "worldwide repercussions, including political ones." Investors were glad to see him go, as shares of UBS rose more than 3% on September 26, 2011 following Grubel's announcement.

The bank's shares had been slumping downward as worse-than-expected earnings weighed on investors.

Amag Pharmaceuticals CEO Brian Pereira

When investors aren't thrilled with a company's plans for growth, it may signal that its CEO's days are numbered.

Amag Pharmaceuticals CEO Brian J.G. Pereira resigned in November 2011 shortly after shareholders voted against the company's plans to issue new stock to acquire lymphoma drug maker Allos Therapeutics. Shareholders had called the plan "ill conceived."

Before executives announced the Allos deal in July, Amag shares had traded above $19. The price tumbled after word of the deal, sinking below $14 by October.

The day Pereira announced his resignation, shares rebounded, closing up 18% to $16.19.