Auctions of Public Debt Securities by the Central Bank of Brazil: A Study of the Factors of the Dispersion of Proposals for BBCs

ABSTRACT

We aim at obtaining a simple econometric model that allows us to build a confidence interval for the dispersion of the bids made by financial institutions at the central bank weekly auctions of short-term securities in Brazil. Under competitive conditions (e. g., no coalition between a few financial institutions) we assume that the bids’ dispersion is associated with the volatility of the daily interest rate futures prices and the daily interest rates that had prevailed during the days prior to the auction. Based on that assumption, our model succeeds in separating the two auctions with extremely high volatility. ln one of them, the high dispersion could be predicted using the other interest rate markets’ data; in the other the dispersion fell outside the confidence interval for the predicted dispersion. This can be used as empirical evidence of an attempt to comer the market that has indeed occurred at that date.

KEYWORDS:
Public debt; public debt structure