The Central Bank of Nigeria (CBN) conducted one of its most aggressive single-session Open Market Operations (OMO) auctions on May 21, 2026, mopping up a combined N3.692 trillion across two instruments in a dramatic escalation of its liquidity tightening campaign.

This is according to OMO auction results published by the apex bank and analysed by Nairametrics.

The apex bank’s financial data show that the combined offer of N600 billion across a 33-day, and a 138-day bill was overwhelmed by investor demand as total subscriptions hit N3.692 trillion, more than six times the amount on offer.

The May 21 auction results reveal a financial system awash with investible funds chasing the CBN’s high-yield paper.

On the 33-day bill, subscriptions reached N1.525 trillion against a N300 billion offer, representing a 5.1x oversubscription, with the CBN accepting the entire amount at a marginal rate of 21.57%.

The longer 138-day bill drew even stronger demand — N2.168 trillion in bids against a N300 billion offer, a staggering 7.2x oversubscription, with all bids accepted at a marginal rate of 19.97%.

The short-tenor bill commanded a higher rate (21.57%) than the longer-dated instrument (19.97%).

The willingness of the CBN to accept all subscriptions — rather than rationing as it did on May 12 signals a deliberate policy decision to drain as much excess liquidity from the banking system as possible in a single session consistent with concerns about inflationary money supply.

Combined net sales of N3.692 trillion in a single day represent an extraordinary intervention by any measure since 2026.

Broader CBN financial data reinforces this picture. The Standing Deposit Facility (SDF) — the primary channel through which banks park surplus cash with the CBN overnight — fell dramatically from N6.103 trillion on May 20 to N5.797 trillion on May 21.