of the DJIA. Significant selling created steep price declines throughout the day, particularly during the last 90 minutes of trading. Deluged with sell orders, many stocks on the NYSE faced trading halts and delays. Of the 2,257 NYSE-listed stocks, there were 195 trading delays and halts during the day. Total trading volume was so large that the computer and communications systems in place at the time were overwhelmed, leaving orders unfilled for an hour or more. Large funds transfers were delayed for hours and the Fedwire and NYSE SuperDot systems shut down for extended periods, further compounding traders' confusion. Margin calls and liquidity Frederic Mishkin suggested that the greatest economic danger was not events on the day of the crash itself, but the potential for "spreading collapse of securities firms" if an extended liquidity crisis in the securities industry began to threaten the solvency and viability of brokerage houses and specialists. This possibility first loomed on the day after the crash. At least initially, there was a very real risk that these institutions could fail. If that happened, spillover effects could sweep over the entire financial system, with negative consequences for the real economy as a whole. As Robert R. Glauber stated, "From our perspective on the Brady Commission, Black Monday may have been frightening, but it was the capital-liquidity problem on Tuesday that was horrifying." The source of these liquidity problems was a general increase in margin calls; after the market's plunge, these were about 10 times their average size and three times greater than the highest previous morning variation call. Several firms had insufficient cash in customers' accounts (that is, they were "undersegregated"). Firms drawing funds from their own capital to meet the shortfall sometimes became undercapitalized; 11 firms received margin calls from a single customer that exceeded that firm's adjusted net capital, sometimes by as much as two-to-one. Investors needed to repay end-of-day margin calls made on October 19 before the opening of the market on October 20. Clearinghouse member firms called on lending institutions to extend credit to cover these sudden and unexpected charges, but the brokerages requesting additional credit began to exceed their credit limit. Banks were also worried about increasing their involvement and exposure to a chaotic market. The size and urgency of the demands for credit placed upon banks was unprecedented. In general, counterparty risk increased as the creditworthiness of counterparties and the