The concept is simple enough, and probably 95% of analysts and financial planners will tell you diversification is one of the key factors in managing the risks associated with any single investment. Just spread your invested dollars across different asset classes, different industries, market caps, global regions or even countries:
Asset classes--
- Stocks, or Equities
- Bonds, or corporate/municipal debt
- Commodities like copper, wheat, natural gas, pork bellies
- Real Estate
- Treasury bills
- Collectibles like art, vintage automobiles, sports memorabilia, fine wines, etc
- Cash, or cash equivalents
Market cap--
- Small cap (company valuation $300 million - $2 billion)
- Mid-cap (company valuation of $2b - $10b)
- Large cap (company valuation upwards of $10b)

But here's the thing: I've been a committed investor for over 20 years, and I've done very well. But I've always been poorly diversified and I have no plan to become more so. My portfolio weathered the tech bubble popping and following pullback from 2000-2003, and the great recession of 2008-2010. It was painful to watch, but I found that patience alone got it done: wait it out and everything comes back.
The problem for me is that diversification requires two things I've been unable to withstand. First, diversifying means investing broadly rather than deeply, which ensures average returns. The more different classes or industries or countries you place your money in, the less any one catastrophe can hurt you-- and the less any one home run can help you. I work hard to position my money just so. I'm swinging for home runs: Apple, Netflix, Starbucks, Tesla.
The problem for me is that diversification requires two things I've been unable to withstand. First, diversifying means investing broadly rather than deeply, which ensures average returns. The more different classes or industries or countries you place your money in, the less any one catastrophe can hurt you-- and the less any one home run can help you. I work hard to position my money just so. I'm swinging for home runs: Apple, Netflix, Starbucks, Tesla.
The second reason, as I've discussed on this blog before, is that I invest in things I know, things I understand, things I already pay attention to. It's the only way I know to get consistently positive returns. When I wander off that path, I fail at a rate close to 50%. And I just don't have enough familiarity or understanding of everything on the planet to intelligently make those choices. Brazil or China? Casinos or publishing or health care? Beats me. I'll stick to my knitting.

A little over 10% of my assets are in real estate, a portion which was once much higher and which I'd like to increase again. And I have about 7% in savings, earning nothing, so I can take advantage of attractive opportunities that come along.

My approach will not work for most people. Normally, investors want to put their money into something safe for a long time, and ignore it. They want asset growth, but also stability and forgettability. That means exchange-traded index funds which are more liquid and lower cost than mutual funds and which move up and down with the entire market, or segments of the market. Since the market always rises over long periods of time, they're happy and they don't have to worry. They don't have to know anything about the companies and they won't be brought down by any big pullback-- in the long run.

Diversification is just not for me.
Drifting to Fifty | Random unrelated nugget of the week
Broaden your musical tastes. Try some jazz, a little R&B, international, even country. The choices are endless, easy to sample, and have never been more inexpensive. Good music enriches your life
and will pay dividends forever.