William Blair & Co. started the William Blair Emerging Leaders Growth Fund, confirmed spokesman Tony Zimmer. The fund, launched Wednesday, plans to invest at least 80% of its assets in emerging markets growth companies with capitalizations of at least $5 billion. The fund plans to invest in 30 to 60 companies, Mr. Zimmer said. It will be managed by Jeffrey Urbina, principal and a co-manager of the $1 billion Emerging Markets Growth Fund and the manager of William Blairs $391 million International Small Cap Growth Fund. William Blair has $58 billion under management, $33 billion of which is for institutional clients.