Standard & Poor’s, the U.S.-based financial services company, made headlines this summer by downgrading the United States’ credit rating, dropping the country from AAA, the top grade, to AA-plus, the second highest. The move sparked debate not only about America’s finances, but also credit-rating agencies themselves. When ratings first appeared in the early 1900s, investors lacked the resources to analyze securities. Agencies filled that gap by compiling data and adding insight. More than a century later, few understand how the agencies operate. S&P says the “primary factor” used to consider creditworthiness is the likelihood of default, assessed partly by determining whether the entity could survive different “stress scenarios,” ranging from the Great Depression to a mild blip. The AAA credit rating means the entity could survive something like an 85% drop in the stock market. In comparison, a B rating means they could withstand a market that falls 10%. But every agency uses different criteria, leading to wildly different ratings for countries. Below, we review the United States’ ranking by various credit agencies, both big and small.