FOR IMMEDIATE RELEASE

JEFFERIES EXPANDS FAMILY OF INDICES TO INCLUDE UNIQUE SETS OF SMALL- AND MID-CAP COMPANIES

NEW YORK, December 20, 2006 -- Jefferies & Company, Inc., the principal operating subsidiary of Jefferies Group, Inc. (NYSE: JEF), today announced an expansion of its family of indices with the introduction of 20 proprietary equity indices to track the performance of small- and mid-cap companies, both domestic and global. The new indices include performance benchmarks of IPOs, companies that have recently repurchased shares or emerged from bankruptcy, and companies in the clean technology and energy sectors, among others. Standard & Poor's, the world's leading index provider, has been chosen by Jefferies to calculate the new suite of indices.

These indices are a natural extension of the firm's focus on and dedication to growing companies and their investors. These instruments will provide a powerful tool for assessing the performance of unique market segments, and they will serve as benchmarks for small- and mid-cap-focused portfolios.

"Jefferies is committed to providing the most sophisticated trading tools and solutions to meet the evolving needs of our institutional customers," said Ross Stevens, Co-Head of Equity Products at Jefferies. "With our robust trading and research coverage of small- and mid-cap companies worldwide, Jefferies is in a strong position to benchmark the performance of these growing segments of the market. These indices will enable our customers to identify new market opportunities, and we look forward to continuing to develop innovative products that enable investors to achieve and measure success," he added.

Jefferies is introducing a number of specialty indices that benchmark the performance of distinct groups of small- and mid-cap equities, including companies who have recently undergone initial public offerings. These indices, which will be differentiated in the market by their small- and mid-cap orientation, will also track the performance of companies with high levels of share repurchases and short interest. In addition, Jefferies is providing broader market benchmarks for micro-cap, small-cap and mid-cap stock performance to facilitate relative performance comparisons across the Jefferies family of indices.

Leveraging the firm's deep coverage of growing companies in the clean technology and alternative energy sectors, Jefferies is also introducing a number of indices benchmarking emerging opportunities in this area. The Jefferies Global Clean Technology Index^SM is a composite index of nearly 50 leading small- and mid-cap companies engaged in clean technology worldwide. The CleanTech index includes companies engaged in solar and wind energy, as well as providers of biofuels, batteries, fuel cells, microturbines, enzymes and catalysts, and crops and seeds. In addition to the composite index, Jefferies is launching targeted sub-indices tracking companies focused on energy generation, energy storage and industrial biotechnology, markets for which widely available performance indicators do not exist.

To complement the firm's strong position in the oil & gas, oil service and maritime shipping industries, Jefferies is introducing a set of targeted energy indices, including the Jefferies North American Small/Midcap E&P Index^SM, the Jefferies Global Oil Service Index^SM, the Jefferies Global Drilling Contractor Index^SM and the Jefferies US Tanker Index^SM, all of which are segments of the energy market previously without dedicated benchmarks.

"As investor interest in clean technology and energy continues to grow, Jefferies has developed a series of exclusive indices to enable our institutional customers to evaluate these sectors and their related investments," said Mr. Stevens. "While related cleantech and energy indices exist in the market today, we carefully analyzed what is currently available in our development of a distinctive offering that provides a level of breadth and depth notable on Wall Street."

Building upon the firm's extensive post-bankruptcy research expertise, Jefferies is launching the Jefferies Re-Org Index^SM. This innovative index reflects the performance of newly-emerged, post-reorganization equities that have effected a re-characterization of ownership through the bankruptcy process. This benchmark may be used by post-reorganization clients of Jefferies. leading restructuring advisory practice and other market participants to track performance in this specialized investment category.

The introduction of this new series of equity indices complements Jefferies' existing index offerings, the Reuters/Jefferies CRB Index and the Jefferies Active Convertible Index (JACI). The Reuters/Jefferies CRB Index, revised, renamed and relaunched in June 2005, is designed to provide timely and accurate representation of a long-only, broadly diversified commodities portfolio and is often cited as the commodity measure of choice. Also, the industry standard JACI index provides an outstanding benchmarking and management tool for global convertible bond portfolio managers. This index has been a valuable resource for institutional investors since its inception in 1994.

For more information about Jefferies' indices and to view important legal disclaimers, visit www.jefferies.com/indices.

About Jefferies

Jefferies, a global investment bank and institutional securities firm, has served growing and mid-sized companies and their investors for nearly 45 years. Headquartered in New York, with more than 25 offices around the world, Jefferies provides clients with capital markets and financial advisory services, institutional brokerage, securities research and asset management. The firm is a leading provider of trade execution in equity, high yield, convertible and international securities for institutional investors and high net worth individuals. Jefferies & Company, Inc. is the principal operating subsidiary of Jefferies Group, Inc. (NYSE: JEF; www.jefferies.com).

For further information, please contact:
Tom Tarrant, Jefferies & Company, Inc., 203 708 5989, ttarrant@jefferies.com