Lennar (NYSE: LEN) has agreed to buy Arlington, Va.-based home builder CalAtlantic (NYSE: CAA) for $9.3 billion in cash and stock (including $3.6 billion in assumed debt). The combined company would have a market cap of around $18 billion.

• Why it's the BFD: Because it would create the country's largest home builder by revenue.
• D.C. context: The National Association of Home Builders will oppose the House GOP's forthcoming tax bill, despite a weekend concession on federal itemized property tax deductions.
• Bottom line: "In acquiring CalAtlantic, Lennar will have access to a new supply of developable land that can be built on quickly, which is less risky than buying large tracts of undeveloped land that could take years to get permits." – WSJ

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