NEW YORK--Merrill Lynch last month announced the launch of Biotech Holdrs, a new security representing 20 varied biotechnology companies, including several genomics companies. The price of the security was $109.18 each when trading began November 23 on the American Stock Exchange under the symbol BBH. 4.5 million Holdrs, representing undivided beneficial ownership interest in the common stock, were initially priced at a total of more than $490 million.