Africa's largest stock exchange said diluted headline earnings per share came in at 470.2 cents for the year to end-December, from 555.9 a year earlier.
Headline earnings per share, which exclude one-times items, are the main performance measure in South Africa.
The JSE said total revenue grew 1 percent to 1.38 billion rand, even as revenue from equity market trades dropped by more than 9 percent.
"This decline was offset by growth in other revenue lines, with notable improvements in both interest rate products and market data," it said in an earnings filing.
It maintained its dividend at 250 cents a share.
Twelve companies were listed on the bourse in 2012, a decline from 16 in the previous year. Bond activity was more robust with listings rising 24 percent to 1,452.
The JSE flagged expenses would rise in 2013 from costs related to its new systems.
JSE shares were little changed at 76.76 rand at 1452 GMT, percent at 1317GMT, in line with the All-share index, which was also little changed.