It will certainly be interesting to see the number of shares outstanding at 30 Sep 2018 and those around Fri 26 Oct (printed at the foot of the front page of the 10-Q) especially as BRK.B has spent half of October at around $215-$224 and then dropped to below $210 and as low as about $197.50 during the session on 26 Oct (I topped up my exposure around that level on Friday).
On the old faithful metric of Book Value Per Share, the quarter probably ended around $228,500 per A or ~$152.30 per B share, but has since dropped thanks to the assumed stock portfolio retracing a lot of its gains, alongside the market in general. I'd guess ~$197.50 was just below 1.3x BVPS at quarter end, but just above 1.3x BVPS when adjusting for the portfolio decline and typical earnings over 26 days. 1,3x BVPS has typically been a good buy point, though the rare times below 1.25x BVPS (e.g. Jan-Feb 2016) are obviously even better and limit the near term downside risk enormously.
My thought is that that ratio of IV to BV has increased a little and this is recognised by Mr Market, and prices significantly below 1.3x BVPS will perhaps be rarer still over future years. BRK purchased at such a price is likely to return inflation+ 6% to 9% compounding with quite a high probability to my mind, and short term downside risk is likely to be limited to about 10% except in the depths of a major bear market, making Berkshire stock at that price a great place to earn a healthy compound return if held long term with a short-term return distribution skewed significantly to the upside, while retaining optionality close to that of cash, allowing me to redeploy my funds at short notice if I happen to find a bargain high conviction opportunity that warrants substantial exposure (and these high conviction ideas might be once in 3-5 year finds so on average I have plenty of time to compound value while I'm waiting). Berkshire also carries, to my mind, very little company risk, because Berkshire has so many diverse earnings streams and autonomously run subsidiaries operating in only modestly correlated areas of the economy, and because it is famously a prudent long-term capital allocator with a strong aversion to permanent loss of capital.
While the opportunities around $185-190 in late July were great buy points to me, I suspect that prices around $198-205 now that the buyback rules have changed will be very likely to have seen significant buyback volume in October, though as SwedishValue points out, it might still do little more than offset the cash inflows from operations given the limitations offered by SEC Safe Harbor guidelines.