I've developed about 15 damn good rules for investing. On IHUB I've expressed them as absolutes even tho I've violated them at times. Buffett mentions his "rules" often. He too makes rare exceptions which someone with legions of lawyers and auditors can do. As for averaging down, BRK's huge size limits what he can buy (and sell). With about 90 mostly blue chip investments, BRK is already highly diversified. I can see him buying more of huge KMI especially since his current holding is small.
On IHUB I express my rules as absolutes because IHUB scam victims and gambling addicts will always find excuses for violating perfectly sensible investing rules.
My 15 rules are pretty conventional. Only 2 or 3 of them are a bit non-standard. After watching too many scammy stocks being listed on the NASDAQ during the Dot Com era I've often advised sticking with the NYSE (a newbie investor could buy the QQQ Nasdaq ETF if he wants to spice up his portfolio with tech). My NYSE-only rule is good for beginners. Since Enron in 2002, Big Board stocks have been remarkably clean. And plenty of garbage can still be found on NASDAQ's lowest tier.
I hold three NASDAQ stocks: Walgreen's recently moved from the NYSE to the NASDAQ. Skyworks was a spinoff from a NYSE blue chip, and the third is a large firm I've owned for years.
While a NYSE listing provides additional investor protection, it won't help much with commodity and leverage risk. SDRL and many other plummeting oils are NYSE.
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