投資心法(1) - 你手上隻股票得4%機率跑贏個債市？

寫呢個Blog，其實係女朋友問到，既然投資呢條路都叫有啲心得，點解唔將個諗法systematic咁寫出黎，見解/心得係有責任傳承落去。諗諗下，都係喎，咁不如我寫低佢，List埋我睇開既reference出黎，做一個紀錄，同時溫故知新。

 

睇得呢個Blog既，相信都係股市/債市/牛市/熊市浸淫過一般時間，咁就當基礎知識都有D認識，唔會講得出AMZN一股3千幾USD, AAPL一股先得幾百USD, 所以AMZN市值大過AAPL幾十倍呢啲misconception架啦。

 

但係，呢個世界，最好賣既，應該係賣希望。只要有希望，人就會一窩峰咁去做，盲目咁將hard-earned money pump落去一個自己都唔認識既product到都得。明明投資市場有好多data，好多quantitative research，但係好多人都係選擇信anecdotal evidence，所以真係有需要做一個myth buster。

 

講完開場白，雖然話systematic咁寫低自己學返黎既經驗，但係都係想講咩就講咩，寫十幾篇之後，應該會有個脈絡出到嚟。

 

好，不如每一次都用個問題形式探討下。

 

「美國股市長牛就係地球人都知，之但係揀美國股票，你會有幾多%機率，可以揀啱股票長揸，然後跑得贏長揸加roll over美國1-month t-bills(即係regarded as無風險既資產)既strategy？」

 

Source:

https://www.universal-investment.com/media/document/Do%20Stocks%20outperform%20Treasury%20Bills

 

嫌長既，可以睇呢段abstract都夠。

 

“The majority of common stocks that have appeared in the CRSP database since 1926 have lifetime buy-and-hold returns less than one-month Treasuries. When stated in terms of lifetime dollar wealth creation, the best-performing four percent of listed companies explain the net gain for the entire U.S. stock market since 1926, as other stocks collectively matched Treasury bills. These results highlight the important role of positive skewness in the distribution of individual stock returns, attributable both to skewness in monthly returns and to the effects of compounding. The results help to explain why poorly-diversified active strategies most often underperform market averages.”

 

答案係4%鬆啲。

 

簡單黎講，股市入邊有4%既公司outperform到長揸一個月treasuries既strategies，然之後其餘96%股票基本上只係勉強match到1M T-bills return。換句話說，啲財經書籍日吹夜吹話股票跑贏債券、樓市等等，其實你係得4%機率揀中股票，揸到間公司執笠，承受過程中既上上落落，然之後跑贏長揸treasuries，仲未計大量其餘有negative return既公司。

 

你自己選股，原來得4%機率拎到excess return，唔怪得知有咁多地球人買股票贏唔到錢/跑輸哂樓市。相反，香港樓市，除左比華利山、超高溢價新盤，如果買傳統屋苑/市區正常樓，基本上跟大市升，升多升少既分別。

呢個係股票同其他asset classes好fundamental ，但往往被忽略既difference。每隻股票個別表現可以好參差，但樓市就無咁明顯，呢種同大市表現有差別既risk叫idiosyncratic   risks，而且對個別股票而言，係大到你唔信。

 

解決辦法：

 

Diversify, 全包圍，買哂所有公司。因為，你有96%機會買唔中outperforming既公司，之後得個吉。買market ETFs，就確保到你基本上好大概率(before fees and commission)跟到大市，咁嗰句「股票跑贏債券、樓市」云云，先對你生效。如果唔係，你有96%機會跑輸債券、樓市，又要每日/晚擔驚受怕，承受extra risk with no extra return。

OK，實有人話「我stock-picking勁到你唔信，今年重倉TSLA, NVDA贏到開巷」，咁OK既，要取得excess return ，retail investors可以做既黎黎去去都係leverage, market timing, 同stock picking呢三大個方法(當然仲有arbitrage，market neutral strategies等等啦, 但retail點夠人地institutional鬥呢)，之後將會逐樣講下我既睇法，同埋點解今年我市都唔洗點睇, TWR 已經一倍有突，而且，係好大機會可以replicate落去。