It is worth noting that many ranking lists have a survey methodology favoring universities and business schools with large numbers of faculty and researchers as well as large graduating cohorts. The Stockholm School of Economics is a small school (with 1 700 students) compared to Copenhagen Business School (with more than 20 000 students).
This question aside, the QS Rankings ranks SSE ninth in terms of its economics program, which places SSE as the leader for economics programs in Scandinavia.
The Financial Times also regularly conducts international rankings of degree and executive education programs, and SSE has been an active participant in FT rankings since 2000. SSE remains the leading Nordic school in the FT European Business School rankings and SSE’s 'Master of Science program in Finance' is ranked by the FT as 13th in the world.
When forming an opinion about an institution of higher learning, it is important not only to review individual rankings, but also to consider a thorough and comprehensive assessment of multiple factors including, for example, the jobs market for graduates, degree programs offered, and pedagogical expertise.
For more information about the QS Rankings methodology.