What do I do if my broker goes out of business while holding stock or cash in my account? Investors are protected in such cases by the Securities Investors Protection Corp. a private, nonprofit corporation created by federal statute that protects stockholders just as the Federal Deposit Insurance Corp. protects bank customers.

In the event of a brokerage failure, SIPC moves immediately to obtain a court-appointed trustee to liquidate the failed firm. The trustee then attempts to transfer customer accounts, in bulk, to healthy brokerages, usually giving customers access to their accounts within three or four weeks.

If no other firm is interested in taking the accounts, the trustee then settles each customer's account on a case-by-case basis, a process that can take one to three months. Customers are invited to make claims for stock or cash contained in the account. If the failed brokerage is holding stock to cover customer accounts, the stock is dispensed to the customers, or the trustee can buy stock on the open market to give the customers.

However, if the stock cannot be located, the trustee is empowered to dispense money to each customer from the SIPC insurance fund, based on the market value of the stock on the day the brokerage failed. The trustee also can give the customers money to cover lost cash that was held for them in the brokerage's accounts. Each customer is insured for up to $100,000 in cash and $500,000 in stock, with a total limit of $500,000 per customer. Why can't I find some stocks listed in the daily stock tables? Stocks only are included in the daily listings if they traded the previous day. Because of the huge flood of orders this week, trading in some stocks has been held up because there are more sellers than the market can absorb.

Usually, such imbalances are cleared up by the markets within an hour or so, but occasionally they can keep a stock from being traded for a day or more. In some cases, including Washington Post Co. "B" stock, which is traded on the American Stock Exchange, a huge difference in the price that sellers are demanding and the price that buyers are willing to pay has kept the stock from trading so far this week. Should I worry if I depend on my stock holdings for dividend income? Generally, no -- a stock's price usually has no effect on the amount of the quarterly dividend attached to it. Holders of stocks for dividend income may have seen a huge drop in the equity value of their holdings, but their income stream should not be affected.

However, there could be indirect long-term worries. If the decline in the stock market portends poorer business conditions ahead, declines in corporate earnings in the coming year could lead some companies to reduce their dividends. If my individual retirement account is in stock, can I shift it into another investment? Yes, within limits.

You may move the money in an IRA account from one investment vehicle to another -- for example, from a stock fund to a money market fund -- but the Internal Revenue Service generally restricts such shifts to once a year. What is a margin call and what does it mean if I get one? Stock bought on margin is purchased with money loaned to the investor by a brokerage and often collateralized by the stock itself. When stock prices fall, brokerages demand more cash or other collateral. If the investor can't meet the margin call, the brokerage can begin liquidating the customer's stock holdings to cover the account. Should that not provide enough to pay back the money borrowed, the investor will still owe to the brokerage. If I put in a stop-loss order, can my broker sell the stock for less than the price I specified? Yes. A stop-loss order specifies merely that once a stock falls to a specific price, it is to be sold. Should the stock fall further in the minutes between the time the sell order is triggered and when the transaction actually takes place, the price of the transaction could be less than the stop-order price. Or, if a stock opens on the market below the stop-order price, that could trigger a sale at less than the specified price. There's been a lot of talk about "specialists" and "market makers" and their roles in the market. What do these people do? Specialists and market makers are the middlemen who handle stock trades. Specialists, who usually work for specialized brokerage firms that only do such work, match up buyers and sellers on the floor of the stock exchange. Market makers, who generally work for large brokerage firms and handle-over-the-counter stocks, do the same thing using a national computer hookup.

This is not strictly a service role -- both specialists and market makers also trade in the stock they handle for their own accounts, stepping in to buy or sell stock themselves to keep the market moving in an orderly fashion. How much of my losses in the stock market can I write off on this year's taxes? And has that changed under the new tax law? In the new tax law, as in the old, the amount of capital loss that can be written off against income is limited to $3,000. There is one slight change: Under the new law, long-term losses -- on investments held more than six months -- can be written off on a dollar-for-dollar basis; under the old law, it took $2 of long-term loss to get $1 to write off against income.

There is one silver lining., Losses this year can be written off against the 38 percent tax rate, rather than next year's 27 percent rate. What does the drop in the stock market mean for my pension? Pensions fall into two general categories, defined benefit plans and defined contribution plans. In a defined benefit plan, the retiree is promised a certain level of benefits, regardless of the performance of the underlying investments. Thus, employes in such plans are unhurt by a market downturn, but if investment performance remains poor, the employer may be forced to put more money into the retirement fund. Defined benefit plans are insured by the federal Pension Benefit Guaranty Corp.

In a defined contribution plan, employers and/or employes make specific contributions to the retirement fund and benefits are determined by the performance of that fund. Thus, individuals who retire when the fund is depressed will receive reduced benefits. If I participate in a profit-sharing or company savings plan and am changing jobs, must I liquidate my holdings or is there a way I can protect them? Tax-deferred savings and profit-sharing plans usually must be rolled over into an individual retirement account when an employe leaves a company. However, some companies do not require that this be done immediately, and any employe who finds that his fund has taken a beating and thinks the market may recover should ask if he or she can leave it for a brief period.

Employes in profit-sharing plans that invest in the company's stock may buy shares on the open market, or they may take the opportunity to diversify into other stocks.