Leucadia National Corp. (NYSE: LUK) and Jefferies Group Inc. (NYSE: JEF) have agreed to join forces in an all-stock merger. The combination will represent more than $3.6 billion in shareholders’ equity. The two are long-time partners and Leucadia is Jefferies largest shareholder.

In the deal, Jefferies’ shareholders (other than Leucadia, which currently owns approximately 28.6% of the Jefferies outstanding shares) will receive 0.81 of a share of Leucadia common stock for each share of Jefferies common stock they hold in a tax-free exchange. The merger, expected to close during first-quarter 2013, is subject approval by both Leucadia and Jefferies shareholders.

Following recent sales and asset redemptions, Leucadia has approximately $2.4 billion in cash and public securities and $960 million of outstanding parent company debt. At August 31, 2012, Jefferies had cash and cash equivalents of $2.8 billion.

According to Jefferies, “As a subsidiary of Leucadia, Jefferies will have greater balance-sheet resilience and flexibility to guard against, and take advantage of, market dislocations and opportunities. Jefferies currently pays substantial Federal income taxes and thus its expected ongoing pre-tax earnings will materially accelerate utilization of Leucadia’s net operating losses, creating incremental value for all shareholders.”

Upon closing, Richard Handler, currently chief executive of Jefferies, will become chief executive and a director of Leucadia, and will remain Jefferies’ chief executive officer and chairman; Brian Friedman, currently chairman of the executive committee of Jefferies and a director, will also remain chairman of the executive committee of Jefferies; and Joseph Steinberg, Leucadia’s president and a director, will become chairman of the board of Leucadia and continue to work full time as an executive of Leucadia. Ian Cumming will retire as chairman of the board and chief executive officer of Leucadia and remain a director.

Jefferies, which will be the largest business of Leucadia, will continue to operate as a full-service global investment-banking firm in its current form. Jefferies will retain a credit rating that is separate from Leucadia’s. Jefferies’ existing long-term debt will remain outstanding and Jefferies intends to remain an SEC reporting company, regularly filing annual, quarterly, and periodic financial reports.

Following the transaction, 35.3% of Leucadia’s common stock will be owned by Jefferies’ shareholders (excluding the Jefferies shares owned today by Leucadia and including Jefferies vested restricted stock units). Leucadia’s board has approved a new share repurchase program authorizing the repurchase from time to time of up to an aggregate of 25 million Leucadia common shares, inclusive of prior authorizations. Leucadia’s board also has indicated its intention to continue to pay dividends at the annual rate of $0.25 per common share, but on a quarterly basis following the merger.

Jefferies & C. Inc. and J.P. Morgan were financial advisors to Jefferies. Citigroup Global Markets Inc. was financial advisor and provided a fairness opinion to Jefferies. Rothschild was a financial advisor to Leucadia, and UBS Investment Bank was a financial advisor and provided a fairness opinion to the Leucadia board.