At today’s close, the NYSE Arca Biotechnology Index will rebalance, meaning some changes and at least one new addition are coming for the First Trust NYSE Arca Biotechnology Index Fund (NYSEArca: FBT).

The $3.7 billion FBT, the second-largest biotech exchange traded fund by assets, tracks the NYSE Arca Biotechnology Index. That index “is an equal dollar weighted index designed to measure the performance of a cross section of companies in the biotechnology industry that are primarily involved in the use of biological processes to develop products or provide services,” according to First Trust.

Agios Pharmaceuticals (NasdaqGS: AGIO), a developer of cancer and cellular metabolism therapies, is the new addition to the NYSE Arca Biotechnology Index. Cowen estimates 1.245 million shares of Agios will be bought at today’s close to add the stock to the NYSE Arca Biotechnology Index, reports Lee Jackson for 24/7 Wall Street.

Nektar Therapeutics (NasdaqGS: NKTR), currently the smallest of FBT’s 30 holdings with a weight of 2.34%, will see over 3 million of its shares purchased at Friday’s close, according to 24/7 Wall Street, presumably boosting the stock’s footprint in FBT.

Exact Sciences, FBT’s second-smallest holding with a weight of 2.56%, will see buying of 1.13 million shares at today’s close while PDL BioPharma (NasdaqGS: PDLI) shares will be gobbled up to the tune of 2.38 million, reports 24/7 Wall Street. PDL Biopharma, which manages a portfolio of patents and royalty assets in the United States and Europe, came into Friday as FBT’s 25th-largest holding with a weigh of 2.81%.