Once your thesis is completed and uploaded to Harvard’s DASH (Digital Access to Scholarship at Harvard), your thesis, as is the case with most scholarly work, is considered to be in the public domain, but the thesis should remain your intellectual property. If you are doing your thesis work at a company, then any work completed at the company needs to be reviewed by their legal department before it becomes public domain. As a matter of course, the Extension School does not sign Confidentiality Disclosure Agreements (CDAs) with companies, and typically thesis projects are not given approval if some other company or lab claims intellectual property rights to your work.
If you are working in a lab, then you are encouraged to work on projects that are, although related to the focus of the lab, of a lower priority and lower risk, in which case consideration of intellectual property rights is rarely an issue that you would need to confront.
For more information, please see the Harvard Library Copyright Advisor program webpage (http://copyright.lib.harvard.edu). Under the "publishing and licensing" section, there is an 8-minute video that explains why scholarly research needs to be public domain.