BOB GARFIELD: We should note, however, that robotically turning out Wall Street stories is nothing new. It's been going on forever – not using computer software, but regular human reporters. As we reported back in 2003, they somehow can absorb all the activity that takes place in all the financial markets on any given day and knock out a story, miraculously reducing it all to its absolute essence. This is the floor of the New York Stock Exchange. [AMBIENT SOUND] Amid the hustle and bustle on Wednesday, the Dow Jones Industrial Average lost 87 points, or just under one percent of its value. The NASDAQ was off 100 points. Why? CNBC seemed to know. [VIDEO CLIP, MUSIC]

ANNOUNCER: Welcome back. A busy news day. The market's moving a little bit lower today, word of a new tape from Osama bin Laden causing the markets to sort of fall off the table there.

BOB GARFIELD: Got that? Over a period of six-and-a-half hours, millions of investors traded billions of shares of stock because of word of a new tape from Osama bin Laden. The day before, both the Dow and the NASDAQ were down because, according to the Associated Press, of a disappointing revenue outlook for Nokia and investor profit-taking. The day before that, according to USAToday.com, the Dow was up 83 points due to optimism about the economy. Really?

RAY GOLDBACHER: That's as reasonable as anything.

BOB GARFIELD: Ray Goldbacher is the money editor at USAToday.com.

RAY GOLDBACHER: You know, every day, three billion shares change hands. Who knows why? I mean the best you can do is try to take the temperature of the predominant trend. Analysts and journalists find ways to explain the market no matter what it does – or try.

BOB GARFIELD: They do try. Every trading day, reporters at the Associated Press, Bloomberg, Reuters, USA Today, The Wall Street Journal and a dozen other news organizations are expected to distill millions of discrete financial decisions and divine a single motivating factor. Some days it's a Commerce Department report on business inventories. Sometimes it's a jump in IBM's earnings. Sometimes it's the mysterious "technical factors" or dropping oil prices or terrorism jitters or investor optimism or the magical, all-encompassing "profit-taking." Dan Gross covers Wall Street for slate.com.

DAN GROSS: Of course there's profit-taking every single minute of every single day. It's a very convenient shorthand for, oh, well gee, we don't know why the Dow went down 70 points.

BOB GARFIELD: But, Gross says, his colleagues do know how to find someone to float a theory.

DAN GROSS: You have a number of sources, guys you know you can call for a quote, and the guys on the other end have a limited number of things that they will say. It was down on profit-taking, up on optimism, concern about profits. You know, there are a set number of factors that everybody will say.

BOB GARFIELD: One source often turned to for the daily analysis is Hugh Johnson, chairman of asset management for the investment banking house First Albany Corporation. With his more than three decades of market experience, Johnson carefully considers corporate fundamentals, external news events, trading patterns known as technicals, the push and pull of other markets such as commodities, bonds and currency trading, and his long-cultivated instinct for the psychology of the trading floor. And then - he guesses.

HUGH JOHNSON: It's a real giant leap of faith to say this is what's been on the minds of investors and made them make decisions, because you obviously don't survey every investor. But you get a sense that the markets tend to respond or react to news in a fairly, fairly predictable way. Having done this for a while, it's probably a pretty good guess that these events do in somehow, some manner, affect investors.

BOB GARFIELD: Or, you know, not. [BAR AMBIENCE] We are in the Irish Punt Saloon, a favorite hangout for brokers and traders, shortly after the closing bell on a sultry summer afternoon. We approach a young Wall Streeter named Anthony Piacosta. I need your expert analysis. NASDAQ was down 21 points today, a little over one percent. Why?

ANTHONY PIACOSTA: Oh, there's a few reasons actually. One of the reasons was that Cisco came out with earnings and their expectations were as great as said to be, and Cisco is pretty much one of the largest of the NASDAQ composites, so it pulls down the average very easily.

BOB GARFIELD: A quick follow-up question: Are you sure?

ANTHONY PIACOSTA: Am I sure? Positive.

BOB GARFIELD: Then we collar his pal, Dieter Uber. The NASDAQ was down about one percent today. Why?

DIETER UBER: The NASDAQ's down now because technicals are taking over. There's, it's like 1675, 1690 we're sitting at. Once it broke that level, now technicals on the NASDAQ are actually taking over, and the traders will just fight to sell, because they're up.

BOB GARFIELD: You sure about that?

DIETER UBER: Yes. As for the NASDAQ being down today, it's because of technicals.

BOB GARFIELD: Then finally we turned to their colleague, Kieran Lockhern, who crunches the same numbers on NASDAQ's dip and draws an entirely different and stunning conclusion.

KIERAN LOCKHERN: It's probably just overheated. You know? Numbers have come out; there's nothing to take us up any further. Now people eventually look at the profits that they have and realize, either take 'em or get off the pot.

BOB GARFIELD: So a little bit of profit-taking.

KIERAN LOCKHERN: Yeah, sure.

BOB GARFIELD: Ah, profit-taking. But if single factor analysis sometimes seems silly or worse, at least one Wall Street watcher staunchly defends the practice. He is David Wilson, managing editor for global stock markets at Bloomberg News, the organization that revolutionized financial journalism with up-to-the-second reports delivered to your desktop. Wilson insists that trading days do follow miniature trends and themes, with certain critical events assuming disproportionate influence.

DAVID WILSON: There are days when it's pretty straightforward. You get a figure - you know, it might be a company earnings, it might be an economic report - and that really does set the tone for the day. And you see it even before trading begins, because you're looking at what's happening overseas with the futures markets, with U.S. stocks traded there, and it may be that whatever the theme is at 8:30 in the morning carries all the way through the day.

BOB GARFIELD: Hence, on Wednesday, according to Bloomberg as well as CNBC, what really mattered was the latest video from Osama bin Laden. Or, you know, not.

LOU DOBBS: I'm very suspicious of anybody who looks at a market monolithically.

BOB GARFIELD: Lou Dobbs of CNN's nightly "Lou Dobbs Tonight" is among the most influential financial journalists in the world. He rolls his eyes at the simplistic art of the Wall Street Market Wrap, but he also acknowledges his occasional complicity because of the time constraints of broadcast television, and, he says, the demands of the audience.

LOU DOBBS: There's not enough space in newspapers, there's not enough time on television or radio to give the explanation as it's deserved. And, frankly, the audience wouldn't want it anyway in most cases, the broader audience, because it is complex, and it takes far too much time. So we revert to traditional shorthand that, while wrong, is expedient.

BOB GARFIELD: What if the press covered Congress the way it covers the Street?

LOU DOBBS: They do. [LAUGHS]

BOB GARFIELD: Well, not really. Although you can certainly say this - this week the House and the Senate blocked a proposed Commerce Department rule that would have limited overtime pay for millions of workers, on concerns about - profit-taking.

BOB GARFIELD: That's it for this week's show. On the Media was produced by Megan Ryan, Tony Field, Jamie York and Mike Vuolo and edited this week – pretty much by me. Dylan Keefe is our technical director and Jennifer Munson our engineer. We had help from Noah Kumin. Our webmaster is Amy Pearl. Katya Rogers is our senior producer and John Keefe our executive producer. Bassist/composer Ben Allison wrote our theme. This is On the Media from WNYC. Brooke Gladstone will really be back next week. This time I mean it. I'm Bob Garfield.