Yahoo! now provides delayed options quote data. To obtain an option chain for a particular company, request a quote for the underlying stock. When the quote result is returned, click the "Options" link under "Quotes" in the left column of the displayed quote. This returns the complete option chain for the closest expiration month in a table below the stock quote. Calls are listed on the top half of the page, and Puts are listed on the bottom half.

How to read the option chain data

Symbol:
A five-character symbol followed by the ".X" extension. The ".X" suffix is the designation used by Yahoo! Finance for U.S. options symbols.

Last Trade:
The time and price of the last trade made for option contract.
Note: Options quotes do not reflect lot size. A single options contract typically covers 100 shares of the underlying security (this might vary in the case of mergers, splits, and index options). Example: An option contract is quoted at $25. Actual option would cost $2500 ($25 x 100 shares).

Change:
The change in price for the day. This is the difference between the last trade and the previous day's closing price (Prev Close). The change is reported as "0" if the option hasn't traded today.

Bid/Ask:
The Bid price is the price you get if you were to write (sell) an option. The Ask price is the price you have to pay to purchase an option.

Volume:
The volume indicates the number of option contracts that have traded for the current day.

Open Interest:
The total number of derivative contracts traded that have not yet been liquidated either by an offsetting derivative transaction or by delivery.

Strike Price:
The stated price per share for which underlying stock can be purchased (in the case of a call) or sold (in the case of a put) by the option holder upon exercise of the option contract.

How to read the detailed quote data

Detailed quotes for options (obtained either by clicking a linked symbol from a chain or by requesting an individual option from the "Get Quotes" box) include the additional fields:

Previous Close:
The closing price for the trading day prior to the last trade reported.

Open:
Opening price for the day; first trade of the day.

Day's Range:
The high and low prices, recorded during the current or most recent trading day.

Contract Range:
The high and low prices, over the life of the contract as of the previous trading day.

Expiration Date:
Date upon which the option expires. Important note: equity, index, and treasury/interest rate options expire on Saturday. Trading of an option effectively ceases on the most recent trading day prior to the expiration date (which is usually a Friday, but might be a Thursday in the event of a Friday holiday).