This is a British Airways business (
I) fare from San Francisco to Basel or Zurich. The price appears at around $2,000 on
Google Flights and Expedia, etc., but for certain routings the price is actually as low as $1,600. The cheaper deal can be found on ba.com and the Amex Travel website, and also by playing around on ITA Matrix. It is available out of BOS as well.
If anyone can figure out the routing factor that results in the $1,600 price rather than $2,000, that would be helpful to know.
Amex Travel example (SFO-LHR-BSL-LHR-DUB-SFO):