Colorado's National Storage seeks at least $300 million as it goes public

National Storage Affiliates Trust, a real estate investment trust based in Greenwood Village that operates self-storage facilities, has set a target of raising $300 million or more in its initial public offering.

The company says it is offering 20 million shares at between $15 and $17 a share, with underwriters getting an option to buy an additional 3 million shares.

The sale of 20 million shares at $15 would raise $300 million; the sale of 23 million shares at $17 would raise $391 million.

The…