BUSINESS WATCH:

They were both born four decades ago this year, and like most twins, South Coast Plaza and Fashion Island have a competitive streak. Over the years, the two malls have vied over sales, publicity, retailers, first dibs on Bloomingdale’s, and even the heights of their respective holiday trees.

Still, there’s little question which one is going all out for its 40th anniversary celebration.

While Fashion Island made do with a few upbeat press releases, South Coast Plaza has embarked on an expensive renovation and plans a monthlong cultural bash in October — which serves as a birthday party of sorts, even though the scheduling was a bit of a coincidence. The mall turned 40 March 15, but the owners had more than a cocktail reception in mind.

“We have decided to have a yearlong celebration rather than one day,” said managing partner Henry Segerstrom.

That celebration involves, in part, $155 million and the Italian government. The mall has embarked on a series of physical makeovers that include new flooring, remodeled stores and a glass observation elevator.

The biggest festivities for the year are expected to come with “Italy at South Coast Plaza,” an exposition of fashion, art, cinema and food presented in collaboration with the Italian Trade Commission. The monthlong event, scheduled to run from Oct. 4 to 29, includes events at a number of the mall’s Italian-themed businesses.

In the days leading up to Oct. 4, artists plan to recreate a Sistine Chapel painting with flowers outside the mall.

For Segerstrom, the Italian partnership was proof of how South Coast Plaza’s reputation has grown over the decades.

“It’s the purpose and intent of South Coast Plaza to achieve a role as the leading quality and luxury retail center in America, and we have achieved that reputation internationally,” he said.

MICHAEL MILLER may be reached at (714) 966-4617 or at michael.miller@latimes.com.