The Dow Jones Industrial Average just announced its biggest shake-up in a decade.

On Sept. 23, Bank of America, Hewlett-Packard, and Alcoa will get the boot from the 30-stock index, and Nike, Visa, and Goldman Sachs will take their places.

The S&P Dow Jones Indices, which makes these decisions, cited "the low stock price of the three companies" and "a desire to diversify the sector and industry group representation of the

index" as reasons for the swap.

market capitalization is $155.6 billion, to $74.5 billion for Goldman. It has 257,000 employees, to 32,000 for Goldman. It is engaged in banking and lending activity in basically every

community in America, as opposed to Goldman’s specialty investment banking business. But when you find yourself in the archaic trap of weighing companies based on their per-share price,

that's the kind of absurdity you end up with. [The Washington Post]

Calling the index "a small batch artisanal stock index" (zing!), Yglesias also warns that the reliance on per-share price is preventing the index from including common sense additions:

The obvious HP replacement, after all, would be Apple — a company that's broadly in the same industry as HP but is now much more economically significant than HP is. But since the DJIA is

price-weighted rather than market-cap weighted companies like Apple that have a very high share price would skew the index too much. So you get no Apple and you get no Google. [Slate]

So don't fret too much over the Dow's shifting members. Really, don't worry too much about the Dow in general. As Irwin says: "It is an accident of history that the Dow is the most widely

cited measure of how the overall stock market is doing, and a bad accident."

Carmel Lobello is the business editor at TheWeek.com. Previously, she was an editor at DeathandTaxesMag.com.