The iShares NASDAQ Biotechnology Index (ETF) has lost more than 26.5 percent since the beginning of the year. Meanwhile experts said taht they do not believe selling the biotech sector right now is a very good idea.Stocks To Buy When questioned about the most recent stock Allianz director John Schroer bought in the pullback, he said it was Pfizer Inc. PFE 0.2%. He also recommended Alexion Pharmaceuticals, Inc. ALXN 1.91% due to its “very highly protected portfolio of drugs.” Other stocks comprised among Schroer’s top picks (well positioned companies with attractive valuations and promising innovation) include: UnitedHealth Group Inc UNH 0.2%Vertex Pharmaceuticals Incorporated VRTX 1.66%Celgene Corporation CELG 0.88%Bristol-Myers Squibb Co BMY 0.76%