TL;DR:
Company proposes a shareholder meeting on a future date to vote for a reverse split.
Proxies are sent to shareholders containing proposals to be voted on.
Shareholders vote on meeting date.
If the split proposal is approved, the board can decide to effectuate a split within the next year.
Board decides on the effective date that the split will occur.
Stock trades split adjusted on the morning of the effective date.
Example of ATER Reverse Split Process
Special shareholder meeting proposed for July 14, 2023.
Proxies (DEF 14A) were sent one month in advance on June 2, 2023.
Meeting was adjourned due to lack of quorum but reconvened on Aug 11th, 2023 and the reverse split proposal was approved. Vote results were disclosed in an 8-K filing.
The company had until April 24, 2024 to regain compliance, so the board decided to wait until March 20, 2024 to announce that March 22, 2024 will be the effective date of the split.
The reverse split is announced, which can be in a press release or 8-K filing.
ATER starts trading on March 22 on a split adjusted basis.
Possible Effect of Stock Splits
A high float stock (>50m) undergoing a reverse split stock will generally experience a drop on the split date.
If there was a prior run-up of the stock before the split, it may also experience a drop on the announcement of the split.
A stock with a low float post split near all time lows may experience higher stock volatility and spikes post split.
Some warrants may have a reset provision that reduces the exercise price of the warrant to the lowest stock price 5 days after the split and simultaneously increase the number of warrants by the same proportion. The effect of will be higher future dilution and capped upside.