I wonder if any companies have considered publishing warrant canaries as part of their public securities filings (for example, inserting it into the risk factors sections).

There is a fairly reasonable argument one could make for doing so:

- The company's value is tied to its reputation for securing its users' data

- An NSL or similar would risk their users' security and the company's reputation

- This will affect the value of the enterprise and therefore the existence of an NSL ought to be disclosed to investors

However at the meta-level, this would be a substantial escalation since an order to continue publishing a canary is no longer just compelled lying, but compelled securities fraud, effectively pitting one branch of government (the national security apparatus) with another (the SEC).