Colin Kaepernick sells shoes.

Online sales spiked for Oregon sportswear giant Nike in the first days of a Portland-produced ad campaign featuring the radical quarterback who began national protests of racial injustice during performances of the national anthem.

San Francisco-based digital marketing firm Edison Trends says Nike's online sales rose 31 percent over the past week—a significant increase from this time last year, when sales rose 17 percent.

"There was speculation that the Nike/Kaepernick campaign would lead to a drop in sales, but our data over the last week does not support that theory," Hetal Pandya, co-founder of Edison Trends, told MarketWatch.

MarketWatch also reports that Nike's stock is steady. Reports in the first 48 hours after news of the ad broke suggested a stock slump—but it's up 1 percent today, and remains up for the month of September.

A two-minute commercial, narrated by Kaepernick and produced by the Portland office of ad agency Wieden + Kennedy, ran in the third quarter of last night's National Football League season opener.

In the days between the ad's announcement and its TV debut, conservatives rent their garments over Kaepernick as a pitchman. Some people burned their Nike gear in viral videos, and President Donald Trump said Nike was making a big mistake.

But ad tracking firm Ace Metrix says the W+K spot, titled "Dream Crazy," received favorability ratings within 10 percentage points of all other ads—suggesting it wasn't really that controversial to most viewers.

"These results show once again that oftentimes, social media backlash can be amplified by media attention while representing only a small minority of haters," Ace Metrix CEO Peter Daboll said in a statement to Ad Age.