Swiss Market Index is just a number that lets you track performance of the instruments comprising the index, so you can't invest in it directly. But you can buy Swiss Market Index futures or funds or invest in its components.
The lowest ever quote of Swiss Market Index is 1279.00 CHF. It was reached on Jan 14, 1991.
Swiss Market Index reached its highest quote on Jan 3, 2022 — 12997.15 CHF.