Ionis Pharmaceuticals Inc. is undertaking a private placement of $507.5 million of 0.125% convertible senior notes due 2024.

Under the agreements, the Carlsbad, Calif.-based biotechnology company will issue $398 million of 0.125% convertible senior notes due 2024 in exchange for its outstanding $340.2 million of 1.00% convertible senior notes due 2021.

Following the closing of the exchange offer, $344.8 million of 1.00% convertible senior notes due 2021 will remain outstanding.

Ionis said in a Dec. 12 press release that it will not receive any cash proceeds from the exchange transactions.

In addition, Ionis will issue $109.5 million of 0.125% convertible senior notes due 2024 for cash and expects to raise about $99.2 million in net proceeds from the transaction.

Ionis plans to use the net cash proceeds to pay costs associated with a convertible note hedge and warrant transactions, which it has entered into with several financial institutions related to the current private placement.

The funds will also be used for general corporate purposes.