Sweden's central bank two weeks ago sold $390 million, but no euros, as part of its new currency hedging scheme, it said on Friday.
Friday's report covering the Sept. 25-29 period was the first of what the Riksbank has said will be weekly information, released with a two-week lag, on how the hedging scheme progresses.
The bank in September announced it would hedge part of its foreign exchange reserves by selling $8 billion and 2 billion euros for Swedish crowns over four to six months to reduce risk. It believes the crown is undervalued.
"The measure is aimed at limiting the Riksbank' losses if the krona appreciates and does not have a monetary policy purpose," it said at the time.
The Riksbank has been concerned that the weak crown is making it harder to bring down inflation.
Earlier this month, it called on the Debt Office to pause its sale of crowns as part of the government's plan to phase out currency exposure from the government's debt portfolio.
"It is unfortunate that the Swedish National Debt Office ... is selling Swedish krona while the Riksbank is buying krona, in a situation where the krona has weakened in an unjustified manner over a long period of time," it said at the time.
"Investors may find it difficult to understand this process." (Reporting by Anna Ringstrom and Simon Johnson, editing by Terje Solsvik)