We study how financial constraints affect the process of firm agglomeration and, in particular, the creation of conglomerates and firms with subsidiaries. We focus on the constraints related to the geographical segmentation of the debt market. We argue that conglomerates/firms with subsidiaries are born as the outcome of a process of agglomeration around less financially constrained firms. This has three major implications: a) conglomerates (firm with subsidiaries) should be less financially constrained than single-segment (no-subsidiary) firms, b) the headquarters – in general the seat of the aggregating company – should be the least financially constrained unit of the new entity and therefore firms with subsidiaries should be more likely to borrow at the headquarters level, c) if conglomerates (firms with subsidiaries) are less financially constrained than the average firm in the market, their Tobin’s Q should be lower than that of the single-segment (no-subsidiary) firms in the same industries – i.e., they should display a “conglomerate (firm with subsidiaries) discount”. We test these hypotheses employing a novel – and exogenous – geographical-based measure of financial constraints. We focus on the US corporations from 1997 to 2004. We show that firms headquartered in less financially constrained areas are more likely to be headquarters of conglomerates/firms with subsidiaries and that conglomerates/firms with subsidiaries are less financially constrained. At the moment of agglomeration (M&A) we document a significant negative relation between the difference in a degree of financial constraints between the bidder and the target and the probability of choosing the target as well as the value created in M&A. In the years following the acquisition Tobin’s Q of acquirers are decreasing relative to their peers which is consistent with the fact that access to lower cost of financing allows to implement projects with marginal Q lower than the average Q of existing projects. Next, we find that the less financially constrained is the headquarters compared to the subsidiaries, the higher is the percentage of the total financing that takes place at headquarters level. Finally, we document a strong positive correlation between the difference in financial constraints of the conglomerate (firm with subsidiaries) and the average degree of financial constraints of the single-segment (no-subsidiary) firms and the conglomerate (firm with subsidiaries) discount. Our findings suggest that conglomerates/firms with subsidiaries are less constrained because less constrained firms take over more constrained ones.