A 板块｜一个“彻底失败”的产品，后来抢了别人的饭碗

The launch of the Vanguard First Index Investment Trust, 50 years ago this month, could have gone better. Jack Bogle, Vanguard's founder, called it “an abject failure”. He had hoped to raise somewhere between $50m and $150m, but got only a little over $11m ($65m today). As the first fund aiming to do no more than track a stock-market index—America's S&P 500—that was available to individual investors, it nevertheless raised hackles. “One conclusion, usually expressed with considerable feeling, is that index funds are a ‘cop-out’ and a fad that will soon disappear,” sniffed an article in the Financial Analysts Journal, published later the same year.

Predictably, the professional stock-pickers whose lunch has been eaten are as furious as ever. “Worse than Marxism,” thundered Bernstein, a broker, in 2016. Last month Terry Smith, a favourite fund manager of British retail savers, spent much of his half-yearly investor letter blaming his long underperformance on “a market which is dominated by so-called passive or index funds”. Full disclosure: your columnist, who used to own units in one of Mr Smith's funds, took this rant as his cue to sell them and reinvest in a global-equity tracker.

B 板块｜经理会操作，资金也会推价格

Index funds themselves are not passive, either. Rodney Comegys, Vanguard's head of equities, explains that managers have more discretion than many investors realise. At its launch, for instance, the First Index fund was too small to buy every share in the S&P 500. So it “sampled” 300 or so of them, a practice others still use today. Managers can also trade to minimise taxable gains, or to avoid getting screwed when everyone knows they must rebalance (when a firm such as SpaceX joins an index, say). Some juice returns by lending stocks to short-sellers for fees.

Most important, and worrying, index funds seem increasingly to influence asset prices. This is not just because they are so big. Prices are set by trades, and slow-trading trackers, even enormous ones, account for a tiny fraction of these. But a series of studies have suggested they nevertheless cause distortions. A particularly widely circulated one outlines the “inelastic markets hypothesis”. This finds evidence that the presence of fixed-allocation funds (such as trackers investing all their assets in shares) ensures $1 flowing into the stock-market pushes up overall market value by $3-8. Others have argued that flows into index funds disproportionately raise the share prices of the biggest firms.