I'm not 100% sure of the reporting regulations, but I found this on Investopedia about
Rule 10b-18 and it's worth following that link and reading the whole article as I provide just an excerpt below, and the article explains that Rule 10b-18 is not mandatory and merely provides conditions that would limit the potential liability against securities fraud rules, so there may be other ways to repurchase than the following and still keep the SEC happy:
The Four Conditions
- Manner of purchase: The issuer or affiliate must purchase all shares from a single broker or deal during a single day.
- Timing: An issuer with an average trading volume less than $1 million per day or a public float value below $150 million cannot trade within the last 30 minutes of trading. Companies with higher average trading volume or public float value can trade until the last 10 minutes.
- Price: The issuer must repurchase at a price that does not exceed the highest independent bid or the last transaction price quoted.
- Volume: The issuer cannot purchase over 25 percent of the average daily volume.
The SEC also specified more detailed disclosure requirements for repurchases. In each quarterly report on Form 10-Q and in the annual report on Form 10-K, the company must provide a table showing, on a month-by-month basis: the total number of shares purchased, the average price paid per share, the total number of shares purchased under publicly announced repurchase programs and the maximum number of shares it can repurchase under these programs or the maximum dollar amount.
Speculation: I would not be surprised to see only very modest buyback activity this quarter, and not to find out about the August and September buybacks (if there have been any) until early November when the 10-Q is released. I suspect Berkshire wants this mostly as an option for future capital deployment and may use it later to prevent the cash pile exceeding the float.
They will be aware that investors will be able to see the average repurchase price each month if they do conduct any repurchases and follow Rule 10b-18, so this might even encourage them to hold off this quarter or wait for a large announced negotiated repurchase from a major holder.
For example, if they were to wait and then start repurchases in October, they might reveal a reduced share count towards the end of October (26th Oct, perhaps) on the front page of the 10-Q, but would not have to disclose the average purchase prices paid in October, November and December until the 10-K is released in February 2019. If they wait until after 26th October, say, they could avoid even hinting at the volume of repurchases until the 10-K is released in Feb 2019.