Investors have shed few tears over the demise of the specialist firms that handled trades on the NYSE floor.

But that has started to change with this summer's market swoon.

Decimalization and the rise of electronic trading have conspired to shrink the ranks of the middlemen who are known as specialists at the New York Stock Exchange and market makers in over-the-counter trading. Many people applauded the shift, believing these so-called buyers of last resort were more apt to take advantage of investors than to maintain "fair and orderly" markets.

But the wild trading of recent weeks has some market players reconsidering that position -- and raising other questions about the recent explosion of electronic trading volumes.

Take Wednesday's dramatic moves in Beazer Homes ( BZH). The Atlanta-based homebuilder's shares fell as much as 42% at one point on rumors the company was facing bankruptcy. Beazer denied the rumors at midday and its stock recovered some losses, though it still shed 18% on the day. (On Wednesday, Beazer shares jumped 14% to $13.04, aided by news Citadel has increased its stake in the homebuilder.)

The rumor-driven selling in Beazer -- as well as in Apple ( AAPL) earlier in the week -- in part reflects short-sellers' ability to generate outsized moves in individual stocks in a jittery market.

But the volatility may be exacerbated by technological and structural changes in the market that has left a vacuum in the human specialists' wake.

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