I don't like to talk in terms of beta and alpha too much because I'd rather call it volatility in market price (instead of beta) and compounding of IV (instead of alpha).
Alpha and beta imply that volatility is the main part of risk and that therefore a more volatile stock should have its actual return adjusted downward according to its beta volatility to create an adjusted 'alpha' return that is lowered to account for the 'risk' implied by beta. As my intended holding period is far beyond the typical 1 year used by alpha/beta proponents, I do not consider I should adjust my return downwards and should simply focus on the business fundamentals and their likely growth and whether I paying or being offered a cheap or expensive price for that intrinsic value.
In other worse, because in overall terms I care only about my overall compound return of my portfolio over 10-30 years, not how bumpy a ride it is to get there (and whether or not I trail the market index in 25-50% of the years), I'm explicitly not adjusting compound returns downward.
In Feb 2016, aside from some shares (perhaps 15% of portfolio) outside my normal trading accounts, I pretty much went 100% BRK.B, selling a fairly full-valued Halma plc position and adding my cash balance to buy as much BRK.B as I could at $124-$125, which was just below 1.2x forward BV (announced 2015Q4 figures at the end of Feb 2016) and was about 1.234x 2015Q3BV. At that time I did consider elements of timing in choosing when to make the trades, as I knew the Q4 figures would be released after close on the last Friday of February, giving me a window during which such low prices could remain available. I anticipated that after the annual report release the stock wouldn't trade quite so low again. It turns out I was within a dollar of the quarter's low when I bought.
My main focus there was value - obtaining a large margin of safety by getting a significant discount to IV. My secondary thought was that the price was unlikely to get any cheaper, so I had a good chance of only seeing gains from then on and it was the time to pull the trigger and buy rather than wait for up to 3 weeks to see if the price fell any lower, which was a small element of consideration of volatility, but also the fact that everyone knew about the 1.2x BV buyback threshold being considered a significant discount to IV.
In that position I anticipated very little downside risk other than a market crash or heavy insurance losses, given the buyback threshold being so near my buy price.
Later in May 2016, Apple was trading around $95 (it actually traded a bit lower before I bought, but I wanted to get my thinking straight on the company before committing large sums to it). At this time BRK.B was trading at $142 and still somewhat undervalued and I sold enough to buy a 25% position in Apple on a trailing 12-month earnings yield of about 9.5% after tough year-on-year comparisons (10.4% yield after backing out net cash) with a belief that earnings would very likely recover and that comparisons would also look better and that I was buying well below IV. That was about as bold as I dared to go on a high conviction idea that carried more fundamental risk than BRK.B. Of my total portfolio I think BRK.B was around 55-60% at this point and I figured that the BRK.B position remaining should alone compound sufficiently to meet our retirement goals but that the Apple position could help us reach them faster. From then until December 2017 I didn't trade - only added more cash to the portfolio as I lacked high conviction ideas due to higher market prices.
In the last three months, I've probably gone from around 55% BRK.B to 72% once I felt confident about the effects of the tax cut on forward BV and IV. Again, value was my primary concern, but in giving up 'dry powder' cash I was giving up something with stable value in the event of a sharp decline in market prices, so I gave a little thought to how much I might gain or lose in the short term on the moderate chance that I found a high conviction opportunity before the fundamental compounding of BRK.B would almost certainly mean I had done better than cash.
I started out with about 10.5% cash position (in GBP) from new savings as of 10th Dec 2017 and bought more BRK.B at about £147 GBP ($196). That trade is one where I mainly focused on compounding but in weighing what I was giving up in terms of cash optionality should a huge bargain appear, equivalent to my May 2016 BRK to Apple trade, I did give a little consideration to the downside risks.
At the time, short of a recession, I figured that an unfortunate BRK.B price action might lead to 12-13% loss at most, unless there happened to be large insurance losses or a major market crash that might increase the market price decline to 30% in the latter case. I also figured that BRK's fundamental compounding was likely to see the 'soft floor' increase to around $196 by around 2019Q1 or 2019Q2 (unless there was a big market crash). I didn't want to miss out on likely 9-11% compounding by staying in cash. I figured also that we'd probably add 8-10% to our cash balance over the following 12-18 months of saving, giving reasonable 'dry powder' to take advantage of any bargains. And I figured that my chances of getting a high conviction opportunity were probably around 25% in that time frame.
All in all, I imagined that (short of a major market crash) in perhaps 70% of cases, BRK.B would be trading at or above my $196 buy price if that bargain came along (assuming a normal 1.2x BVPS to 1.6x BVPS trading range), and in about 25% of cases it would be below my buy price by up to 13%, and in about 5% of cases it would be between 14-30% down due to a deep market crash. So I considered I was unlikely to lose a lot of optionality, and I stood a good prospect of making a gain on BRK.B before that bargain came along and I'd be fairly certain of 9-11% compounding long term, which exceeds my retirement return assumption of 3.5% above inflation long-term. Comparing that to cash - it has a negative return after inflation but preserves its nominal value in the event of stock price falls no matter what, allowing me to take advantage of bargains. To me Berkshire provided enough probability of being able to participate in future bargains with the high likelihood of more than sufficient long-term compounding, so I made the trade, taking me to around 67-69% BRK.B (68.82% at year end 2017).
On 8th and 9th Feb 2018 BRK returned to around $192-$196 (now only £137-£141 GBP thanks to a weaker USD) as markets generally fell. I had small positions in IBM and Wells Fargo that I wasn't as sure about as BRK.B for the future and some additional cash to contribute too, and I sold IBM one day in my wife's account (prior to going ex-dividend, I think) and bought as much BRK.B as the increased cash balance allowed.
The next day we had added quite a bit more cash by transferring bank balances around (without risking our day-to-day requirements or emergency funds) and added it to my trading account. I had a target number of BRK.B shares I wanted to buy using the cash plus Wells Fargo stock. A reasonable looking price came for WFC so I sold that. I patiently waited for about 40 minutes more until BRK.B dropped just enough to buy the amount I was seeking at around $192.
Before today's open, with BRK.B at just under $198, cash is 0.01% (though I'll get Apple dividend and my final Wells Fargo dividend soon and add more cash in March), BRK.B is 71.75% and AAPL is 25.83%. I estimate that both my main positions are trading at a discount to IV and should have good prospects to compound per share fundamental value at least 9-11% in the long run.
Apple is more likely to suffer temporary declines and has the greater but still acceptable risk of permanent loss of value of the two. Annoyingly I lose 30% of every AAPL dividend to the US government, but my capital gains of 73% in USD, 81% in GBP, are tax-free so I can't complain really. If Berkshire becomes extremely cheap (e.g. $180 at present) I may consider that it's a sufficiently better prospect than AAPL to go all-in on BRK.B.
