Business technology company Slack made Portland as a finalist for a second headquarters that could employ 550, according to officials in another state.

However, Slack apparently has already chosen a different city.

"We're continuously evaluating different markets for expansion," Slack said in a written statement. "At this time, we're confirming a new office in Denver."

The San Francisco company makes an instant messaging app widely used among technology professionals and in other large offices to encourage collaboration and open communications.

Officials in Colorado's economic development agency approved $10.5 million in incentives Thursday in hopes of luring Slack to Denver, according to the Denver Business Journal.

Colorado officials said Slack is also considering Phoenix, Arizona; Austin; and Portland. They said Slack is dangling jobs that pay an average wage of nearly $108,000, which is on par with the average wage in Oregon's tech industry.

The economic development agencies for Portland and Oregon both said they had not been in contact with Slack for this project. That suggests Slack may have already settled on Denver by the time Colorado officials publicly suggested Portland as a rival site.

Still, Oregon's economic development agency it wouldn't be surprising if Slack had considered Portland.

"Companies now know about what we have here, with the nexus of high tech industry on both the hardware and software sides, the workforce that's developed over time, the quality of place we have with diverse regions (and) a thriving economy," said Nathan Buehler, an agency spokesman.

Last year, Bloomberg reported Slack was raising $250 million from investors who valued the company at $5 billion altogether. The company claims more than 8 million daily users from 500,000 organizations.

Oregon has long been a second home for many large tech companies, drawn to the region by a high concentration of tech professionals and relatively low operating costs. Companies with large outposts include Airbnb, Amazon, eBay, Google HP Enterprise, HP Inc., Salesforce and Google, among many others. Intel employs 20,000 in Washington County, its largest site anywhere.

When Amazon considered a second headquarters that could eventually employ close to 50,000, though, Portland made a subdued pitch that offered no special incentives.

Oregon is enjoying a long economic expansion that has pushed unemployment down to 4.1 percent, its lowest growth on record. Tech has fueled much of that growth, but the concentration of high-wage jobs clustered in and around downtown Portland has contributed to rising housing costs and other strains.

This article has been updated with additional comment and Slack's statement.

-- Mike Rogoway; twitter: @rogoway; 503-294-7699