Editor's note: This article has been corrected to reflect that only four of the departing employees were portfolio managers. The rest were investment professionals (analysts, researchers, etc). In addition, we clarified that the departing managers were part of a team that managed 21% of assets under management.

It's nothing new for top Wall Street execs to be lured away by rivals. The recent news, however --that four portfolio managers and 12 investment professionals of Amvescap (NYSE:AVZ) have told the firm "auf wiedersehen" to set up shop at Deutsche Bank (NYSE:DB) -- is turning heads.

According to reports, Deutsche exec Kevin Parker met with Amvescap CEO Martin Flanagan last Friday to inform him of the group's departure, including that of the fixed income group's chief investment officer, and to propose a monetary sum to dissuade any legal battles over any contractual concerns. Instead of accepting the offer, Mr. Flanagan wrote an email over the weekend to the particular employees promising to at least match the rival offer and to "convey his commitment to the group." The firm also set its sights on legal remedies and filed suit to seek unspecified damages from the Deutsche unit, alleging it schemed to "raid illegally" its staff, a claim Deutsche refutes by saying instead that it was approached by several of the Amvescap employees.

Mr. Parker was busy sending email as well. Last Sunday afternoon, he wrote to Mr. Flanagan telling him, in a nutshell, that it was a lost cause to try to change the minds of the defecting employees, and that Amvescap might be a lost cause, too. According to The Wall Street Journal, he opined that the defection "would undoubtebly [sic] result in near total asset loss."

Not so fast, Mr. Parker. While you may be gloating at the chance to build inroads into the U.S. market, let's look at the facts. The 155-person fixed income group that these managers were a part of managed approximately 21% of Amvescap's total assets under management. Assuming that the managers bring their accounts with them, that's a sizeable chunk, to be sure. It's also one comprising fixed income and stable value investments, which typically generate lower fees than other products.

It's unlikely that this episode will drive the company under on a strictly financial basis. However, Amvescap must contend with the effects -- beyond the firm's implicit morale problem -- that gave root to the exodus. These include a legal battle that drains attention and resources, coupled with the accompanying publicity, which can scare potential investors away from both its products and its stock. It's also quite clear now that the battle among investment managers over even lower-yielding assets has intensified.

While Amvescap has tried to plug its holes, its American depositary shares have tumbled 8.3% from last Friday through the end of yesterday's trading session, a sizeable discount which may soon result in an upward bounce. The firm has reshuffled its managers and rattled its sabers in public. Still, the new managers must reconstruct a track record in these investment classes and its CEO must rebuild internal loyalty. While Amvescap may not be saying "auf wiedersehen" itself any time soon, the firm has its work cut out for it.

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Fool contributor S.J. Caplan  does not own shares of the companies mentioned.