I'm old enough to remember when the Biotech HOLDRs came out in late 1999 ... I guess they're a Van Eck product now. The most liquid biotech ETF is IBB, followed by XBI.

Merrill Lynch Introduces Single Security Representing 20 Biotech Stocks
Monday, November 22, 1999 05:59 PM

Merrill Lynch, Pierce, Fenner & Smith Incorporated today announced the launch of Biotech HOLDRs(SM), a new security representing undivided beneficial ownership interest in the common stock of 20 specified companies involved in various segments of the biotechnology industry.

Today, 4.5 million Biotech HOLDRs were priced for initial sale to the public at an aggregate offering price in excess of $490 million. Trading of Biotech HOLDRs begins on Tuesday, November 23, 1999, on the American Stock Exchange under the symbol "BBH." Newly issued Biotech HOLDRs will be available on a continuous basis.