Like other hospital-related stocks, Tenet rose sharply from October 2012 through March 2013 — starting with the time when it seemed likely that President Obama would be re-elected and that the A.C.A. would be implemented. The law was considered a boon for hospitals because it was expected to increase usage and reduce the expense of caring for uninsured patients who could not pay their bills.

Most of Mr. Bush’s Tenet share sales were on Oct. 2, 2013, at a time when two events in Washington were creating uncertainty for health care companies and threatening to unwind the bull run for health care stocks driven by Mr. Obama’s re-election. Oct. 2 was the second day of the government shutdown, precipitated by Senator Ted Cruz’s demand that any bill to keep the government open also “de-fund” the health care law. It was also the second day that HealthCare.gov was supposed to be in operation, but users were not having much success navigating the site to buy health plans.

In retrospect, we know those twin threats were not able to stop the health care law, and perhaps the financial markets knew it at the time: Tenet shares were actually up 6 percent on Oct. 2, 2013. The company had completed its acquisition of a rival, Vanguard Health Systems, the previous day — part of a broader trend of consolidation in the health care industry.