According to the sources provided, there are several companies that hold active patents for olaparib in the United States. Olaparib is a drug used for the treatment of ovarian and breast cancer, and it falls under the category of PARP inhibitors.

The first source, Drug Patent Watch, provides a comprehensive list of patents related to olaparib. However, it requires a subscription to access the specific details of each patent. Unfortunately, without a subscription, it is not possible to provide specific information about the companies holding the patents from this source.

The second source, FiercePharma, provides a list of top 15 blockbuster patent expirations, but it does not mention olaparib or any specific companies holding patents for this drug. Therefore, it does not provide relevant information for this question.

The third source, a research article published in the National Center for Biotechnology Information (NCBI), discusses the development and approval of olaparib for the treatment of ovarian cancer. While the article provides valuable information about the drug, its clinical trials, and its efficacy, it does not mention the specific companies holding active patents for olaparib in the US.

In conclusion, based on the sources provided, we cannot determine the specific companies holding active patents for olaparib in the United States. It is recommended to consult additional sources, such as the United States Patent and Trademark Office (USPTO) database or legal databases, to obtain more specific information on the companies holding patents for olaparib.

Sources:
[1] Drug Patent Watch. (Accessed on 14 November 2021). Available at: https://www.drugpatentwatch.com/p/tradename/OLAPARIB
[2] FiercePharma. (Accessed on 14 November 2021). Available at: https://www.fiercepharma.com/special-report/top-15-blockbuster-patent-expirations-coming-decade
[3] National Center for Biotechnology Information. (2019). Olaparib: First Global Approval. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6812612/