Martin Marietta seeks a rocky relationship.

• Position: Triangle - Geographic overview

Martin Marietta Materials Inc. sold 14 billion tons of rock for $1.6 billion in 2010, but the Raleigh-based company's most lucrative haul may have come last May when it dug into the financial records of Vulcan Materials Co., its largest competitor. Martin Marietta then launched an unsolicited bid in December for Birmingham, Ala.-based Vulcan, which is suing Martin Marietta, contending that its use of confidential information in an unfriendly takeover bid was the pits.

Both CEOs agree the road to impasse was paved with good intentions when talks began last May about a merger of the nation's two largest construction-materials companies. Vulcan opened its books--the contents of which Martin Marietta agreed to keep confidential--but rejected the resulting offer, which CEO Donald James called "low-ball" He believes both companies are rebounding from the recession but that Vulcan, which has more employees, quarries and rock reserves, is better positioned. Martin Marietta CEO Ward Nye says his company has a higher stock price and lower debt.

Martin Marietta is offering Vulcan shareholders half a share of its stock for each of theirs--a roughly 15% premium in early December--valuing Vulcan at about $4.7 billion based on recent stock prices. Some Vulcan shareholders sued the company because it won't agree to the deal. Vulcan sued Martin Marietta, claiming it's using confidential information in its takeover bid. Martin Marietta sued Vulcan, contending that a confidentiality agreement can't block a hostile takeover, and is asking shareholders to elect five of its nominees to Vulcan's board. There's also a chance the U.S. Justice Department could squash the merger before it starts.

The coming months will determine if the companies are really at odds or just performing the ritual sparring that public companies often engage in before merging--one trying to drive its price up and the other, down. Both hint at a possible quick resolution. If that happens, shareholders shouldn't fret that the current nastiness means an acrimonious match. "People might say, 'Oh, that's like a forced marriage, and it's going to be an awful relationship," says Steve Jones, professor of organizational behavior at UNC Chapel Hill's Kenan-Flagler Business School. "But either the deal happens or it doesn't. If it does, everybody becomes very pragmatic."

RALEIGH--Triangle Capital raised roughly $77 million in a secondary stock offering. The finance company plans to use the proceeds...