The Swedish krona is not a major currency in this pair, while the USD certainly is. The krona is required by treaty to be replaced by the EUR at one point. The USD/SEK is not a commodity pair.
By every measure, the US Dollar is the most dominant currency of the forex scene. It is by far the most traded and it is also the most popular reserve currency. That is just the tip of the iceberg though. The USD permeates every nook and cranny of the global economy. It is the currency in which gold and oil are traded, it is the benchmark for establishing the value of new startups and it is indeed the fiat measure of the strength and value for cryptocurrencies.
The USD is the official currency of 7 other countries, and 23 countries have their currencies pegged to the USD. The Federal Reserve controls the USD.
Introduced in 1973, the Swedish Krona lived to see the Scandinavian Monetary Union, which included Sweden of course, Norway and Denmark. Initially on the gold standard, the SEK survived the above said monetary union, though it is now threatened to be gobbled up by yet another – much more ambitious – similar experiment: the Eurozone.
Although under obligation to replace the SEK with the EUR, Sweden has thus far steered clear of the Eurozone, by avoiding to join the European Exchange Rate Mechanism, which is a necessary step for Euro adoption.
Though the SEK is indeed distinct from the EUR, given the close trade relations between Sweden and the EU, it is closely correlated with the common currency. Despite that, the SEK does tend to move about independently from the EUR, so the trading opportunities on the USD/SEK are different than on the EUR/USD. Sweden’s exports to the US are definitely a factor to watch in this regard.