DMJM will take 125,000 sf for 15 years at Shuwa Corp.'s twin-towered Arco Plaza on Flower Street. The company will move from its longtime Westside home at One Park Plaza in late September, bringing more than 500 workers with it.

Though DMJM and Shuwa officials won't disclose financial terms, sources familiar with the transaction say the lease is probably worth between $45 million and $50 million. GlobeSt.com and its sister print publication, Real Estate Southern California, reported earlier this year that the deal appeared imminent.

Several relatively large leases have been signed in the CBD over the past several months, but none as large as the 125,000 sf taken by DMJM. Yet, the deal's importance goes far beyond sheer size.