Europe's biggest insurer Allianz defended its U.S. asset management business Pimco on Wednesday as it came under fire for failing to stem the flow of heavy investor withdrawals. Allianz is under pressure from some shareholders to step up oversight of Pimco, the world's largest bond investor with nearly $2 trillion in assets, because of a run of poor returns and the departure of CEO Mohamed El-Erian amid a row with co-founder Bill Gross. But the insurer's chief executive said that investors needed to ignore short-term volatility and take a longer-term view, pointing out that Pimco had produced better returns than many of its competitors for large parts of the past 25 years. "There is really no reason to rake us over the coals or to sense the end is at hand," Michael Diekmann told the insurer's annual shareholder meeting in Munich. Diekmann said customers had been supportive of the creation of a new team of six deputy chief investment officers to support G