Quiet Filing
  
See: Shelf Registration. See: Regulation A.
What a prisoner does to his cell bars late at night when he’s getting ready to escape.
Also, in the financial world, the term refers to a way to prepare for an initial public offering, while still withholding some information about the company.
When a company files for an IPO, it has to submit certain documents to the SEC. These include information about the company and about the projected offering. In a quiet filing, the company doesn't fill in all the boxes. It purposely leaves out some information. This strategy only works in the early stages of preparing an IPO. All the info has to come out eventually. But the company can initially leave out a lot of the pertinent information and then disclose the details later via amended filing documents.
It's a way of delaying the release of key facts about the company until the firm is absolutely sure that it wants to go through with the IPO. Like...how you didn't tell your fiance about all the previous times you got engaged until after the wedding.