Diversification
Spreading money across many places rather than betting it all on one stock or asset to reduce risk — the practice of "don't put all your eggs in one basket."
In plain terms
You know the saying "don't put all your eggs in one basket"? Drop the basket and all the eggs break. Diversification spreads money across many stocks and sectors rather than piling it into one, so the whole does not collapse if one goes wrong.
The key is spreading across things that "move differently." Holding only similar stocks that all rise and fall together gives little diversification benefit. You have to mix things of different sectors and character for risk to truly fall.
What it tells you
Diversification comes from the humility of "I do not know the future." Unable to be sure which stock will do well, you spread across several so that even if one fails there is room to recover.
Diversification is not a tool to maximize returns but one to protect against being wiped out by a single big failure. "Not losing" is the winning path over the long run.
Formula
diversification = spreading investment across many stocks, sectors, and assets that move differently, so that one collapse does not bring the whole down with it
What high or low means
Too concentrated in one stock or sector and the blow is big when it goes wrong. Conversely, too finely diversified and it is hard to manage and the return turns ordinary, so a proper balance matters.
Gathering only assets that move the same way looks diversified but does not actually reduce risk (e.g. 10 tech stocks only).
Beware the illusion of "I bought several, so I diversified." If they are all the same sector and character, they can fall together, so the key is not the number of stocks but "do they move differently."
Conversely, over-diversification can be "a pile of investments with no conviction." The hard part is the balance between concentrating on what you know well and managing risk.
Enron, which went bankrupt in 2001, has a painful story. Many Enron employees had concentrated their retirement savings in "Enron company stock" as the company encouraged. They trusted the company.
When it collapsed, they lost their job (paycheck) and retirement money (pension) at once — the price of putting everything in one basket (their own company). It is the most painful demonstration of why diversification is "protective investing" and how dangerous it is to bet everything on one place.
Metrics to read alongside
See it in real stocks
Search US stocks on Stocklore to see Diversification and other financial metrics alongside the sector average.
This explanation is for information and reference only and is not a recommendation to buy or sell any security. Investment decisions and their consequences are your own.