"Considerable index passive-type funds usually buy at the closing prices, they don't want to take any intra-day risk," said Craig Stent, executive director and head of equities at Harbour Asset Management.
"There are people that buy for index reasons, but there are also hedge funds and people that arbitrage this so they get ahead of it and they do the opposite of what the index fund is doing. So there's lots of noise but when it comes to the crunch at the end of the day, not much tends to happen in terms of the share price in these bigger companies."
Synlait was the best performer, up 5.1 per cent to $11.25, with Mercury gaining 2.4 per cent to $3.23. Tourism Holdings fell 2.1 per cent to $6.53.
"In the smaller companies - inclusions or exclusions, their share price might be a bit more volatile," Stent said. "Some of these companies with less spotlight on them, their share prices might move around a bit more."
Restaurant Brands dipped 1.1 per cent to $7.78. Along with joining the small-cap index, the fast-food operator announced it had lifted first-quarter sales 12 pe rcent to $180 million after it acquired a further 13 KFC stores in Australia. It also shed rights to an 18 cents per share dividend.
Trustpower was the worst performer on the index, down 4.4 per cent to $5.65, after shedding rights to a 17 cents per share dividend. Air New Zealand fell 3.5 per cent to $3.13, Sky Network Television dropped 3.3 per cent to $2.32, and Meridian Energy declined 2.1 per cent to $2.985.
Outside the benchmark index, ikeGPS dropped 15.3 per cent to 50 cents. The unprofitable laser measurement tool maker narrowed its annual loss after lifting sales 37 per cent and cutting a fifth from its wage bill and is optimistic positive cash flow generated in the fourth quarter will persist, meaning it won't need to raise more capital.