Traded 71     opment and trading of exchange-traded funds, discussed in Chapter 4. The national ex- changes are willing to list a stock (allow trading in that stock on the exchange) only if the firm meets certain criteria of size and stability. Regional exchanges provide a market for trading shares of local firms that do not meet the listing requirements of the national exchanges. Table 3.2 gives some initial listing requirements for the NYSE. These requirements en- sure that a firm is of significant trading interest before the NYSE will allocate facilities for it to be traded on the floor of the exchange. If a listed company suffers a decline and fails to meet the criteria in Table 3.2, it may be delisted from the exchange. Regional exchanges also sponsor trading of some firms that are traded on national ex- changes. This dual listing enables local brokerage firms to trade in shares of large firms without needing to purchase a membership on the NYSE. The NYSE recently has lost market share to the regional exchanges and, far more dra- matically, to the over-the-counter market. Today, approximately 70% of the trades in stocks listed on the NYSE are actually executed on the NYSE. In contrast, about 80% of the trades in NYSE-listed shares were executed on the exchange in the early 1980s. The loss is at- tributed to lower commissions charged on other exchanges, although the NYSE believes that a more inclusive treatment of trading costs would show that it is the most cost-effec- tive trading arena. In any case, many of these non-NYSE trades were for relatively small transactions. The NYSE is still by far the preferred exchange for large traders, and its mar- ket share of exchange-listed companies when measured in share volume rather than num- ber of trades has been stable in the last decade, between 82% and 84%. The over-the-counter Nasdaq market (described in detail shortly) has posed a bigger competitive challenge to the NYSE. Its share of trading volume in NYSE-listed firms in- creased from 2.5% in 1983 to about 8% in 1999. Moreover, many large firms that would be eligible to list their shares on the NYSE now choose to list on Nasdaq. Some of the well- known firms currently trading on Nasdaq are Microsoft, Intel, Apple Computer, Sun Mi- crosystems, and MCI Communications. Total trading volume in over-the-counter stocks on the computerized Nasdaq system has increased dramatically in the last decade, rising from about 50 million shares per day in 1984 to over 1 billion shares in 1999. Share volume on Nasdaq now surpasses that on the NYSE. Table 3.3 shows trading activity in securities listed in national markets in 1999.       Table 3.2 Some Initial Listing Requirements for the NYSE