(CNBC) — Citigroup’s Automated Trading Desk (ATD) had trading losses of around $20 million stemming from Facebook’s botched initial public offering on Nasdaq OMX Group’s U.S. exchange, a source with knowledge of the situation said on Friday.

The unit’s losses were in addition to claims by market makers Knight Capital Group and Citadel Securities, which each had losses of $30 million to $35 million.

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