How do investors choose stocks? - Richard Coffin

936,485 views ・ 2020-11-10

TED-Ed


Please double-click on the English subtitles below to play the video.

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Every day, billions of stocks are traded on the New York Stock Exchange alone.
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But with over 43,000 companies listed on stock exchanges around the world,
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how do investors decide which stocks to buy?
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To answer this question, it’s important to first understand what stocks are,
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and what individuals and institutions hope to achieve by investing in them.
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Stocks are partial shares of ownership in a company.
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So by buying a stock, investors buy a share in the company’s success—
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or failure— as measured by the company’s profits.
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A stock’s price is determined by the number
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of buyers and sellers trading it;
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if there are more buyers than sellers, the price will increase, and vice versa.
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The market price of a share therefore represents
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what buyers and sellers believe the stock, and by association the company,
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is worth.
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So the price can change dramatically
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based on whether investors think the company has a high potential
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for increasing profitability— even if it isn’t profitable yet.
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Investors aim to make money by purchasing stocks
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whose value will increase over time.
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Some investors aim simply to grow their money at a faster rate
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than inflation diminishes its value.
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Others have a goal of “beating the market,”
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which means growing their money at a faster rate
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than the cumulative performance of all companies’ stocks.
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This idea of “beating the market” is a source of debate among investors—
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in fact, investors break into two main groups over it.
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Active investors believe it is possible to beat the market
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by strategically selecting specific stocks and timing their trades,
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while passive investors believe it isn’t usually possible to beat the market,
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and don’t subscribe to stock picking.
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The phrase “beating the market” usually refers to earning a return
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on an investment that exceeds the Standard & Poor 500 index.
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The S&P 500 is a measure of the average performance
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of 500 of the largest companies in the United States,
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weighted by company valuation,
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meaning that companies with a higher market value
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have a larger effect on the S&P—
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again, market value corresponds to what investors
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believe a company is worth rather than actual profits.
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The S&P doesn’t directly represent the market as a whole—
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many small and mid-range stocks can fluctuate according to different patterns.
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Still, it’s a pretty good proxy for the overall market.
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It’s often said that
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“the stock market behaves like a voting machine in the short term,
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and a weighing machine in the long term”—
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meaning short term fluctuations in stock prices reflect public opinion,
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but over the longer term, they do tend to actually reflect companies’ profits.
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Active investors aim to exploit the short term,
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“voting machine” aspect of the market.
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They believe the market contains inefficiencies:
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that stock prices at any given point in time may overvalue some companies,
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undervalue others, or fail to reflect developments that will impact the market.
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Active investors hope to exploit these inefficiencies by buying stocks
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they think are priced low.
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To identify undervalued stocks,
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they may investigate a company’s business operations,
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analyze its financial statements, observe price trends, or use algorithms.
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Passive investors, by contrast,
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put their faith in the long term “weighing machine” aspect of the market.
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They believe that even though markets may exhibit inefficiencies at any given point,
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over time those inefficiencies balance out—
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so if they buy a selection of stocks that represents a cross-section of the market,
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over time it will grow.
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This is usually accomplished through index funds,
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collections of stocks that represent the broader market.
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The S&P 500 index is one of many indexes.
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The overall goal is the same for all index funds:
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to hold stocks for the long term and ignore short-term market fluctuations.
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Ultimately, active and passive investing aren’t mutually exclusive—
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many investment strategies have elements of each,
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for example, choosing stocks actively but holding them for the long term
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as passive investing advises.
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Investing is far from an exact science:
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if there was one foolproof method, everyone would be doing it.
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