IBB entered Wednesday with a small year-to-date loss, but the fund has jumped more than 2% since the start of May.

“Critics say the law, which does not guarantee access the medications, will not have any appreciable effect on the status quo since supplies of investigational drugs are limited because developers earmark them for clinical trials,” according to Seeking Alpha.

Some patient advocacy groups, including the American Cancer Society Cancer Action Network, Friends of Cancer Research and the National Organization for Rare Disorders, oppose the right to try proposal.

Year-to-date, investors have pulled $1.19 billion from IBB.

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