In the last two years of the boom, CDOs created by one bank commonly purchased slices of other CDOs created by the same bank. Market leader Merrill Lynch outpaced its competitors. Nearly half of all of its CDOs bought significant portions of other Merrill CDOs. (About Our Data)

The black circles below represent the number of deals in which banks' CDOs held a significant portion of their own prior CDOs (more than one-third of the overall CDO slices in the deal) while the colored circles represent the total number of deals completed by that bank in that half year.

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Source: Thetica Systems