According to an email seen by ETF Stream, the ComStage portfolio composition files (PCFs) database was “corrupted” amid the move from Commerzbank to Lyxor.
PCFs are the reason ETFs can stay accurately priced throughout the day and are an important piece of the plumbing in the ETF ecosystem.
They enable market makers to price ETFs accurately as they show what is in an ETF at any given moment in the trading day.
Without an accurate PCF, market makers are unable to correctly price an ETF.
Production of the PCFs for ComStage's physically-replicated ETFs re-started last week, however, some synthetic ETFs are still an issue.
Lyxor said in a statement: "We immediately identified the issue which has only affected a limited number of synthetically replicated ETFs and have been actively working to resolve it.
"Overall, trading on the primary market has not been impacted and the quality of the secondary market has remained high; bid-ask spreads are in-line with longer term averages and market maker presence on-exchange has remained high.
"Lyxor would like to stress that despite some operational teething problems which can occur in business integrations of this magnitude, this does not call into question the fact that the combination of Lyxor’s and Commerzbank’s EMC asset management businesses in Germany has overall gone very smoothly from an operational standpoint and has been seamless for our clients."
As part of this, Lyxor has opened an asset management arm in Germany, which unites its and Commerzbank’s active and passive investment activities under one roof.
The firm revealed the final full merger of the two ETF ranges will completed by mid-2020.
Europe’s third largest ETF provider gone through a tough period this year amid rumours parent company Société Générale is looking to sell the arm. According to data from Morningstar, Lyxor saw ETF outflows of €1bn in Q3, the most across all providers in Europe.