Khanna and Yafeh hypothesize that business groups should be more common in economies with less developed markets and institutions. We test the time-series version of this hypothesis by looking at changes in Chilean groups over 20 years (1990Chilean groups over 20 years ( -2009Business groups are prevalent in emerging markets (e.g., Brazil, India, China, South Korea) and developed markets (e.g., Italy, Sweden). Yet, despite their extended presence, we know little about why they form and how they evolve. Khanna and Yafeh 2007 put forward several hypotheses in this respect. One hypothesis is that business groups should be more common in economies with less developed markets and institutions. Basically, business groups act as substitutes for capital, goods, or labor markets when frictions are severe. A first approach to test this idea is to make cross-country comparisons on the prevalence of business groups as a function of variables that proxy for market development. A second approach is to use within-country, time-series data to see whether business groups correlate with market dynamics. The time series approach has the advantage of controlling for country unobservables that blur cross-country comparisons.In this paper we contribute to the literature on business groups precisely by performing a country-study in the style of the second approach described above.