05-019 · EVIDENCE B · SOURCE-SENSITIVE
Don’t put all your money into one stock, one platform, or one property
别把钱押在一只股票、一个平台、一套房上
No cost at all. The hard part is accepting that you won’t always pick the single most profitable option.
As long as multiple assets don’t all rise or fall in perfect unison, spreading your money across them keeps your average expected returns the same, while reducing the ups and downs of your account balance. Conversely, if you invest all your funds in just one stock, platform, or property, any trouble with it directly impacts your entire portfolio.
B
Move “Don’t put all your money into one stock, one platform, or one property” to Future Me's calendar
The excuse
One more exception feels free because the bill arrives outside the current scene.
What feels good now
Today I keep a few minutes, a bit of persistence and avoid interrupting my default routine.
What the source says
The source summarizes the return this way: “As long as multiple assets don’t all rise or fall in perfect unison, spreading your money across them keeps your average expected returns the same, while reducing the ups and downs of your account balance. Conversely, if you invest all your funds in just one stock, platform, or property, any trouble with it directly impacts your entire portfolio.” Evidence grade B. The original states the population, caveats, and sources; this is not a personal forecast.
Use the original facts and limits. For an urgent medical, safety, financial, or legal issue, contact a qualified local professional or service.
THE ENGLISH EDITION
Original recommendation and evidence
19. Don’t put all your money into one stock, one platform, or one property
Cost: No cost at all. The hard part is accepting that you won’t always pick the single most profitable option.
In plain terms: As long as multiple assets don’t all rise or fall in perfect unison, spreading your money across them keeps your average expected returns the same, while reducing the ups and downs of your account balance. Conversely, if you invest all your funds in just one stock, platform, or property, any trouble with it directly impacts your entire portfolio.
Benefit: When several assets do not move in perfect lockstep, diversifying your investments maintains your expected returns while lowering overall volatility. This is the core conclusion of Markowitz’s 1952 portfolio theory, which has remained foundational for decades. On the other hand, putting all your money into one single stock or platform means its variance becomes your total portfolio variance — any rise or fall in its value directly affects your portfolio, with no other assets to offset losses when problems arise.
Evidence grade: B
Sources: Markowitz, H. (1952). Portfolio Selection. The Journal of Finance, 7(1), 77–91. <https://doi.org/10.1111/j.1540-6261.1952.tb01525.x>
Notes: This is rated as a B grade because the original academic paper relies purely on mathematical derivation, without providing concrete figures on exactly how much diversification reduces potential losses. Diversification can only lessen the fluctuations of your portfolio balance, it does not guarantee you won’t suffer any losses. Buying broad-based index funds (see item 17 in this section) is the easiest way to achieve effective diversification. This information is not intended as investment advice.
Read the complete Chinese source and notes
19. 别把钱押在一只股票、一个平台、一套房上
成本: 不花钱。难的是要接受一件事：你不会正好押中最赚的那一个。
说人话: 几样东西只要不是完全一起涨、一起跌，把钱分开放，平均能赚到的不变，账户的起伏却会小一些。反过来，钱全押在一只股票、一个平台、一套房上，它一出事，就等于你全部出事。
收益: 只要几项资产不是完全同涨同跌，把钱分开放，预期收益（平均能赚到的）不变，波动（账户上下起伏）却更小。这是 Markowitz 1952 年提出的组合选择基本结论，此后几十年一直沿用。反过来说，钱全押在一只股票或者一个平台上，它的方差就是你全部的方差，它涨跌多少你就跟着涨跌多少。出事的时候没有任何对冲，也就没有别的资产能帮你补回来
证据等级: B
来源: Markowitz, H. (1952). Portfolio Selection. The Journal of Finance, 7(1), 77–91. <https://doi.org/10.1111/j.1540-6261.1952.tb01525.x>
备注: 定成 B 级，是因为那篇经典文献是纯数学推导，没有算出「分散能少亏多少钱」的实际数字。分散只能让账户的涨跌小一些，不保证你不亏。买宽基指数基金（见本节第 17 条）本身就是最省事的分散办法。不构成投资建议。
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