@YourHigherBrainFunctions
My interpretation of institutional racism is probably not the typical description. What you've described would be top-bottom institutional racism, which I do believe exists sometimes in areas of politics. It's more likely in politics as racism is a belief oftentimes, and can incorporate itself into political support. Minority groups also tend to have an affinity for one political party, so it could be profitable to some political actors to lessen their political impact. One would have to target minorities indirectly, as you mentioned no institution has obviously racist design behind it, but it's still a viable political strategy.
However, I don't believe top-bottom institutional racism is likely in public businesses in the area of hiring, where race usually isn't a metric that can help profitability and thus is typically disregarded. Perhaps in choosing what ideas and products will be sold it can be present, as that falls in line with appealing to the beliefs of the public. But in general, I believe it's more bottom-up in economic affairs.
I mostly believe that if one assumes a percentage of every race is racist, then minorities will be hurt more by racism than the majority race if they are not significantly more racist than said majority. On a national scale, minorities are more likely to interact with people of different races since they compose less of the population, and thus are more likely to interact with people racist against them. Regions where minorities are greater parts of the population have less of this effect internally, but if you bump the problem up to how wealth flows between regions, the effect becomes present again. I believe that is the main source of the economic disparity. The economic disparity itself can also reinforce this a bit, as it means the minority has less economic impact on average than the majority race.