Target (NYSE:TGT) said today that the retailer's longtime chief executive, Gregg Steinhafel, would be stepping down from his post as CEO effective immediately. The seemingly sudden change of leadership at the discount chain comes on the heels of a cyber breach that left as many as 70 million customers vulnerable to identity theft and saw information from 40 million credit and debit cards stolen. But Steinhafel's 35-year history with Target suggests there is more to this decision than the recent data breach. Let's look at what this means for the company and its shareholders going forward.

Times are a-changin'
In a sign that investors aren't happy with the impromptu resignation of Target's CEO, shares of the stock have fallen more than 3% on the news today. Stocks typically rally when a chief executive steps down, particularly when said company has been under pressure as Target has in recent months. In addition to the data breach, Target's weak entrance into the Canadian market last year also likely contributed to Steinhafel's decision to leave the company.

Steinhafel, who has been at the helm for the past six years, oversaw Target's expansion in the Great White North, where Target opened 124 stores last year. Unfortunately, the retailer's initial push into Canada was plagued by weak traffic that forced Target to cut prices by as much as 90% at times, according to The Wall Street Journal. Target lost as much as $1 billion from operations in Canada last year on fiscal 2013 sales of $1.3 billion.

Target's chief financial officer, John Mulligan, will take over for Steinhafel as interim CEO until a replacement is named. This is a challenging time for the retail chain as it struggles with mounting costs from its expansion into Canada and ongoing security measures at its U.S. stores. For investors, the sooner Target's board can find a new CEO, the better.

Winning back consumer's trust
Target recently hired a new chief information officer to oversee the company's IT security. Bob DeRodes joins the retailer with an impressive background of security work that includes his role as a former senior IT advisor to the U.S. federal government. With a strong team in place to better protect Target on the IT front, the company now needs fresh leadership at the top that can turn things around in Target's Canadian business.

There's a lot at stake for shareholders, particularly as Target has invested nearly $4 billion in its expansion into Canada. On top of the sheer cost of its move into the Canadian market, Canada offers Target a major growth opportunity that should pay off down the road with the right CEO leading the company. One of Steinhafel's strengths was his knowledge of merchandising. This is something that the new CEO should have solid experience with as well. After all, Target's exclusive design labels and celebrity collaborations are one dynamic that continues to work well for the retailer, despite the company's recent setbacks.

Target is set to report first-quarter earnings on May 21. But we could see investors push the stock lower if the company doesn't appoint a new chief executive by that time. For the upcoming quarter, analysts forecast an 11% drop in earnings to $0.73 per share. Sales in the first quarter are expected to inch up just 2% to $17.04 billion in the period.