She earned the season trophy, determined over seven competitions across three continents, by winning the women’s 50 metre butterfly race in Stockholm in 25.3 seconds on Sunday and a silver in the 50 metre freestyle on Saturday.
Alshammar led the women’s points tally ahead of Julia Smit of the US and Hinkelien Schreuder of the Netherlands. The runners-up received $50,000 and third-place finishers $30,000.
Her performance capped a dominant performance for the Swedish team at the 25-metre competition held at Stockholm’s Eriksdalsbadet.
In the 50 metre breaststroke, teammate Jennie Johansson won gold in 30.1 seconds, while Joline Höstman came in third, clocking in at 30.93.
Meanwhile, sprinter Sarah Sjöström won the 100 metre freestyle in 53.13 seconds and silver in the 100 metre backstroke in 58.83.
Martina Granström and Petra Granlund won the silver and bronze in the 200 metre butterfly, while Stina Gardell won the 400 metre individual medley.
In men’s action on Sunday, Lars Frölander won the 100 metre butterfly, while Stefan Nystrand came in second in the 50 metre freestyle and Simon Sjödin took the bronze in the 200 metre medley.
Other Swedish medallists over the weekend included Magdalena Kuras, Rebecka Ekelund and Jakob Dorch.
The men’s trophy was won by Brazil’s Thiago Pereira, who edged out South African swimmers Darian Townsend and Roland Schoeman.