Last week’s news that AbbVie (NYSE: ABBV) will pay $21 billion, or $261.25 per share in cash and stock, for Pharmacyclics (NasdaqGS: PCYC), a maker of cancer treatments, in what represents the largest takeover of a biotech company in 15 years underscores a couple of points.

First, valuations are racing higher for the biotech industry and its takeover targets. Second, makers of cancer therapies and treatments, are commanding the higher end of those lofty premiums.

As has been documented, several biotech exchange traded funds are intimately levered to the oncology, a group that includes the $747 million Market Vectors Biotech ETF (NYSEArca: BBH). BBH is one of the more straightforward funds on this list as it is dominated by biotech’s “big four.” Gilead Sciences (NasdaqGS: GILD), Amgen (NasdaqGS: AMGN), Celgene (NasdaqGS: CELG) and Biogen Idec (NasdaqGS: BIIB) combine for over 41% of BBH’s weight. [M&A Puts This Biotech ETF in Focus]

Gilead, which recently announced a dividend and a $15 billion buyback, and Biogen each have oncology-related therapies. Amgen and Celgene have four a piece. Among other cancer treatments, Amgen makes Prolia, which was developed to help patients suffering from bone marrow loss attributable to hormonal cancers. Celegene’s oncology lineup includes Revlimid, which treats cancers of the blood. [Gilead Could Goose Biotech ETFs]

However, those factoids merely scratch the surface of BBH’s oncology exposure. Not only does the ETF feature a 5% weight to Pharmacyclics, but eight of the ETF’s top 10 holdings, a group that combines for over two-thirds of the ETF’s weight, are involved with oncology treatments.