A Beoing 737 Max. File photo: Xinhua

Boeing on Tuesday officially pushed back the timeframe for the 737 MAX to return to the skies, overshadowing an earlier announcement of a first flight of the delayed 777X plane.

Boeing said it is now targeting the return of the grounded MAX "during mid-2020," the latest delay in the schedule for the troubled jet, which has been grounded since March.

Boeing shares finished at $313.37, down 3.3 percent, after the New York Stock Exchange earlier halted trading for around 40 minutes.

Boeing has told customers and suppliers "that we are currently estimating that the ungrounding of the 737 MAX will begin during mid-2020," the company said in a statement.

That marked a shift from Boeing's most recent stance on its top-selling aircraft when it eliminated a target date entirely after repeatedly failing to keep to timetables in 2019. 

But even the vague mid-2020 target is later than some analysts had expected and it probably represents a best-case scenario that could again be pushed back.

The Federal Aviation Administration (FAA) had publicly criticized Boeing for continually touting its aggressive timeframe in public for the MAX's return, suggesting the target was a tool for pressuring the agency into approving the plane more quickly.

On Tuesday, an FAA spokesman reiterated that it has set "no timeframe" for the MAX's certification.