BioCryst Pharmaceuticals Inc. investor Great Point Partners LLC said it will vote against the company's proposed merger with Idera Pharmaceuticals Inc.

In a letter, the investment manager said it believes BioCryst shares are undervalued and that the merger is "significantly unbalanced." The investor said that under the deal, "highly valuable" BioCryst assets will be transferred to Idera shareholders in exchange for the latter's assets, which are of "more uncertain value."

Great Point, which owns 7,478,275 BioCryst common shares, urged directors to reconsider the transaction and explore alternative strategies.

BioCryst President and CEO Jon Stonehouse said in January, when the deal was announced, that the merger would "create sustainable shareholder value well beyond what either would achieve separately."