"I was wondering if anyone could share their thoughts on proper positioning sizing while maintaining material exposure to high conviction ideas. For example, fellow members of the board have in the past stated they were comfortable with a 50% weight in Berkshire. Why 50%? What would an appropriate baseline weight be for say, GOOGL or MSFT?"

I'm in the camp that views BRK as a lot closer to an "index of profitable companies" than a single company. The outsized weight I give it (over 50%) is built on this premise, and I don't extend it to any other equities.

There are a lot of assumptions built into this belief, all of which I'm pretty confident in: the basic integrity of management; the legal structure of BRK is such that a bad bet or two won't sink the ship; the internal diversity of its profitable businesses (railroads, insurance, tech/consumer goods, etc.); the notion that tomorrow won't look too much different than today; etc

So I suppose I'd say I reject your premise somewhat. In my mind portfolio weight can and should take into account the entity behind the ticker, and there are no hard and fast limits for that reason.