You can always tell what investors think about a company's leadership by how its shares perform once those leaders leave. Shares of PDL BioPharma (NASDAQ:PDLI) rose more than 4% yesterday, after a longtime board member, currently the company's interim CEO, departed.

At PDL BioPharma's annual meeting on Wednesday, interim CEO and board member Patrick Gage resigned from his seat on the board of directors, citing "differences of opinion" about PDL's objectives. Interestingly, Gage had already announced several weeks ago that he would resign once PDL finished spinning off its royalty-generating assets into a new company, a move scheduled to take place by the end of 2008.

PDL's board of directors has endured considerable turnover recently. The company gave no specifics on why Gage left -- much like board chairman Karen Dawes, who left for "personal reasons" on Wednesday as well. Counting these two departures, five of PDL's board members have resigned since last year.

This type of board turnover usually only occurs when malfeasance or a dramatic change of strategy occurs at a company. Considering that there's no sign of the former, the latter -- combined with a healthy dose of shareholder activism from investors like PDL's co-founder Cary Queen -- is the likely reason for the board turnover.

PDL confirmed after the annual meeting that its plans to split the company in two remain in place. Other drugmakers, including Enzon Pharmaceuticals (NASDAQ:ENZN), are planning similar moves.

The last time a PDL CEO left the company in August, shares rose more than 10% the following day. If PDL can keep repeating this maneuver, it may have found a winning strategy to increase its share price. All kidding aside, as long as the drugmaker remains focused on separating its pipeline assets from its royalty revenue, and returning the latter  to shareholders, PDL is poised for a brighter future.