Oliver HirtArno Schuetze 1/2 A logo logo is seen at the seat of Swiss stock exchange operator SIX Group in Zurich, Switzerland June 17, 2019. REUTERS/Arnd Wiegmann Read More ZURICH, June 30 (Reuters) - Switzerland's no.3 telecoms group Salt is preparing for a Zurich stock market flotation in the autumn in a deal that could value the company at about 2.5 billion Swiss francs ($2.7 bln), three people close to the matter said. French entrepreneur Xavier Niel is seeking an exit after seven years of investment, they added. The company is expected to sell shares worth roughly 700 million Swiss francs ($757 million), mainly new shares from a capital increase, the people said.