The power companies mostly gained after government data showed renewable energy generation was at a 37-year high in the June quarter. The Tiwai Point smelter, the country's biggest power user, is close to restarting its fourth potline after a six-year break, Meridian Energy said.
Genesis Energy rose 1.2 per cent to $2.575, Meridian increased 1.2 per cent to $3.40, Trustpower advanced 0.2 per cent to $6.06 and Contact Energy gained 1 per cent to $5.90. Mercury NZ was unchanged at $3.35.
Williamson said the energy companies remained in demand with their relatively high dividend yields.
Among the blue-chip stocks, A2 Milk Co rose 0.9 per cent to $12.38, Mainfreight increased 0.3 per cent to $29.90, Air New Zealand declined 0.2 per cent to $3.17 and Fletcher Building decreased 1.4 per cent to $6.23.
Spark fell 2.1 per cent, or 8.5 cents, to $3.98, after shedding rights to dividends of 12.5 cents per share. Chorus declined 0.5 per cent to $4.975. Williamson said both telecommunications stocks hit respective records yesterday and investors were taking some profit on recent gains.
Other stocks to go ex-dividend include Port of Tauranga, which fell 1.4 per cent, or 7 cents to $5.08. It shed rights to an 11 cent dividend. Comvita gave up rights to a 2 cent dividend, but rose 2.8 per cent, or 18 cents, to $6.65.
Restaurant Brands New Zealand gained 0.9 per cent to $7.73 after reporting a 12 per cent increase in second-quarter sales. Williamson said the fast food operator was showing good signs of same-store growth as well as benefitting from its international expansion.
Outside the benchmark index, Briscoe Group increased 0.9 per cent to $3.53. The retailer increased first-half profit 2.7 per cent and raised its interim dividend for an 11th straight year.