but first to susie gharib, anchor of the "nightly business report" here on pbs. she joins us from the new york stock exchange. susie gharib, first of all, it's being reported there may have been human error involved in that plunge today. what have you learned about it? >> well, it may have been human error, judy, and that may have been compounded by some electronic trading. here's what we know so far. there were two events and we don't know which came first and if they were connected. one thing was that around 2:30 today, mysteriously, shares of procter & gamble and 3m suddenly plunged. and that triggered some electronic trading. also today, a trader accidentally placed an order for $16 billion instead of $16 million of what's called e-minis these contracts traded on the chicago mercantile exchange. we don't know which came first and if they're connected. our sources are telling us the trader was working for citi. citigroup has not confirmed that yet. but that was part of what was going on. you know, i want to say you just did your greece report. before this free

this is "nightly business report" with susie gharib and tom hudson. "nightly business report" is made possible by: this program is made possible by contributions to your pbs station from viewers like you. thank you. captioning sponsored by wpbt >> susie: good evening, everyone. worries about too much debt in europe triggered a big stock market sell-off around the world today. tom, behind the selling-- serious questions about that plan to bail out greece. >> tom: susie, on wall street, the dow tumbled 225 points, the nasdaq plunged 74, and the s&p 500 lost 28 points. volume picked up considerably on both the new york stock exchange and the nasdaq. but the one silver lining was the u.s. dollar-- it rose as the euro fell to a one-year low against the dollar, thanks to the european debt worries. >> susie: the crisis of confidence comes as investors worry about the greek debt crisis spreading to other countries in europe. we have two guests to analyze the issues-- a wall street market strategist, and a top economist from the international monetary fund. th

this is "nightly business report" with susie gharib and tom hudson. "nightly business report" is made possible by: this program is made possible by contributions to your pbs station from viewers like you. thank you. captioning sponsored by wpbt >> susie: good evening, everyone. more selling on wall street today with all the major indexes closing in the red on new worries about the european financial system. tom, this time investors reacted to the bailout over the weekend of a troubled savings bank in spain. >> tom: susie, caja sur is a small bank, but it could spell bigger problems for european debt crisis. the bank of spain took it over, giving it access to about $690 million in emergency money. >> susie: the euro today also fell sharply again against the u.s. dollar and other major currencies. it has dropped 7% in the past month alone. the big question here is whether these cracks in the european system will affect american companies and our economy. joining us now to talk more about this, mohamed el-erian, c.e.o. of pimco, the world's largest bond

this is "nightly business report" with susie gharib and tom hudson. "nightly business report" is made possible by: this program is made possible by contributions to your pbs station from viewers like you. thank you. captioning sponsored by wpbt >> tom: good evening. violent demonstrations in greece today left three people dead in athens. susie, thousands of workers took to the streets, protesting tough cost-cutting measures that the greek government says are needed to pull the country out of a severe debt crisis. >> susie: tom, those demonstrators are angry about cutbacks including wage freezes, higher taxes, and cuts in pension benefits. those austerity measures are conditions set by the european union and the international monetary fund in exchange for giving greece $145 billion in bailout money. >> tom: the situation is so serious that greece's prime minister said the country is, quote, "on the edge of the abyss" and there are worries about contagion. moody's today said it might cut portugal's debt rating. >> tom: the clashes and concern about euro

for that, we're joined again by susie gharib, anchor of pbs's "nightly business report". susie, thanks for joining us again. what-- what more is known today about what happened yesterday? >> you know, it's hard to believe but they're still trying to figure out what happened. it turns out that decoding what happened yesterday is not so easy. there are very complex systems at work here. officials here at the new york stock exchange as well as the nasdaq and regulators are investigating. here's what we know tonight. at first it was thought it was human error. now turns out that is too simple an explanation. the focus now is on computerized trading. it appears that some dramatic moves in the currency markets yesterday may have triggered computerized program selling in the stock markets. and once that happened, the stock transactions were like a domino effect. anything that was available to sell was sold. also today a lot of fingerpointing going on between the new york stock exchange and the nasdaq, the blaming who was really at fault here. the chicago mercantile exchange said

this is "nightly business report" with susie gharib and tom hudson. "nightly business report" is made possible by: this program is made possible by contributions to your pbs station from viewers like you. thank you. captioning sponsored by wpbt >> susie: good evening, everyone. investors cautiously tip-toed back to the stock market today, after yesterday's massive sell off. tom, all the major averages closed up, but there was still a wave of heavy selling at the open. >> tom: susie, it was a choppy day and at the start of trading. the dow fell below the psychologically important 10,000 level. but it stayed above its flash crash low. by late morning, buyers came back and it finished higher by 125 points. still a lot of worries about financial problems in europe, even though a trillion dollar bailout package got the okay from german lawmakers today. as erika miller reports, investors and traders on wall street are not convinced the selling is over. >> reporter: you don't have to go to an amusement park to take a wild ride these days. just invest in the