Compare to your best choice

Suppose you have one hour of free time. You can play cricket, or study for tomorrow's exam, or watch TV. If you choose TV, the price you pay is not just the TV time - it is the best other thing you gave up, maybe the study that would have helped your exam. That given-up best choice is called the opportunity cost. It is the value of the next-best thing you did not do.

Charlie Munger said this is the right way to make every decision. Do not ask "is this good?" Ask "is this better than my next-best choice?" Because saying yes to one thing means the money, time, and attention it eats up are no longer free for anything else. A share that returns some money can still be a bad decision - if you had a better choice available and you skipped it to buy this one. (Return just means how much your money grows - if ₹100 becomes ₹109 in a year, that is a 9% return.)

This sounds obvious, but people forget it all the time, because most people judge a choice alone - "does this share look nice?" - instead of against the field - "is this the best use of this rupee right now?" Munger always did the second. He and Warren Buffett held only a few shares, not because they could not find many okay ideas, but because once you know your few best ideas, putting money into your twentieth-best idea is really taking it away from your best ones. That is why they thought "spreading your money thin just for the sake of it" was strange: adding a so-so share pulls your money away from your strongest one. This study is about reading every decision as a comparison, where the thing you measure against is your best other choice - not zero.

The key move is to pick the right thing to compare against. A weak investor compares a choice to doing nothing - leaving money in the bank - and thinks, "this beats the bank, so yes." (The bank rate is the small, safe return you get just for keeping money in the bank.) Munger compares it to his best other choice and asks, "does this beat the best thing I could otherwise do with this money?" The bar to clear is not the safe bank return. It is your own best idea.

Two things follow from this, and both go against what most people do. First, holding only a few shares makes sense. If you can rank your ideas from best to worst, your money belongs in the best few. Every rupee you put in a weaker idea is a rupee taken away from a better one. So adding your tenth-best idea actually lowers the quality of your average rupee. This is not showing off - it is just maths. Second, keeping cash and waiting is a real, brave choice, not being lazy. If nothing on offer beats your best choice - and that includes simply keeping your money ready for a better chance later - then the right move is to wait. Munger and Buffett often sat on cash for a long time. They were saying no to every idea available because none of them cleared the bar set by the ones they liked more.

Opportunity cost also changes how you think about selling. Holding a share is an active choice to keep your money there instead of moving it to your best other choice. So for anything you own, the real question is not "has it gone up?" but "if I had this cash today, is this still where I would put it, out of everything available?" If the answer is no, you are keeping it only out of laziness - and paying an opportunity cost every single day.

illustrative Kabir finds a solid company he expects to return about 9% a year. That is comfortably more than the roughly 5% he would earn in the bank, so looking at it alone, it seems an easy yes. But at the very same time, he already owns - and understands well - a company he expects to grow at 14% a year. Opportunity cost changes the whole picture. To buy the 9% company, Kabir must either sell some of his 14% company, or spend fresh money that could have gone into it. Measured against the right bar - his own best choice at 14%, not the 5% bank - the 9% "good investment" is actually a value-losing decision, because every rupee it uses gives up 5 extra points of yearly growth it could have earned in the better company.

The lesson is not that 9% is bad. It is that "good on its own" is the wrong test. The investor who compares every idea only to the bank will happily gather a pile of decent-but-weaker shares, slowly pulling money away from their best ones, and then wonder why their returns are only average. The investor who compares every idea to their best other choice puts the money in the 14% company, waits when nothing beats it, and lets opportunity cost do the sorting. Same choices, very different results - decided by what you compare against.

Holding only a few shares makes a wrong guess hurt more. Opportunity cost says put your money in your best few ideas - but if your guess about which is "best" is wrong, holding just a few turns that one mistake into a big loss. Munger could hold just a few because he also fiercely avoided ruin and only ever bought things he truly understood. Holding a few without those two habits is not discipline - it is a giant bet on your own guessing, which can be wrong. The higher bar only helps if your guesses are honest.

Guessing future returns is really just guessing. The whole method rests on comparing returns you cannot actually know for sure. It is easy to fool yourself that your favourite idea is the "14% company" and to skip sensible spreading of money on the strength of a hopeful guess. Opportunity cost is a tool for sorting ideas you can genuinely judge - not a free pass to bet everything on the one you happen to like.

Sometimes spreading money is wise, not weak. Munger's dislike of over-spreading assumes an investor who can reliably rank ideas and stay calm when prices jump around. Most people cannot do both. For them, spreading money over several shares is a sensible defence against being wrong, not a sign of weak nerves. The "hold only a few" argument is strongest for people with real skill and a cool head, and weaker - sometimes even backwards - for those without.

The habit - measure every choice against your best other choice, not against nothing - works for everyone and is one of the clearest tools an investor can carry. What you should copy more carefully is the conclusion Munger drew from it: holding only a few shares. That was right for him because his ranking skill and calm were rare, and he never risked ruin. For a normal Indian investor, the same opportunity-cost logic supports some focus on a few truly-understood ideas - but not throwing away all spreading of money, because the honest input (your ability to guess future returns) is much weaker. So take the bar (your best other choice, and the patience to wait when nothing beats it), and focus your money only as much as you actually trust your own rankings.

• Measure against your best idea, not the bank. An option that beats the bank can still be a bad choice if it spends money your best idea needed.
• Treat holding as a fresh choice. For everything you own, ask: if I had this cash today, is this still where I'd put it, out of everything available?
• Let focus follow your ranking - money belongs in your best few ideas - but only as far as you truly trust those rankings.
• Count waiting as a choice. If nothing on offer clears the bar, keeping cash for a better chance is the disciplined move, not laziness.
• Be honest that guessing future returns is guessing - don't use a hopeful guess to justify betting too much on one idea.