"That has obviously upset the price today, on the basis that after people get their big payout in September this year, they may look to switch," Lindsay said.
Infratil, which is Trustpower's controlling shareholder, dropped 1.5 per cent to $3.22, making it the second-worst performer on the index. Separately, Wellington-based Infratil said it has finished its NZ Bus negotiations in Wellington, with contracts to begin in the second half of this year. NZ Bus has secured five long-term contracts in the capital, and the deal is "consistent with Infratil's market messaging on the expected future scale of the NZ Bus business and earnings guidance."
A2 Milk Co rose 2.4 per cent to $9.28, while Vector gained 2.4 per cent to $3.41.
Outside the benchmark index, Oceania Healthcare fell 5.6 per cent to $1.02. The Auckland-based aged-care operator, which listed on the NZX last May, reported first-half profit nearly doubled as its investment property became more valuable and it sold more retirement village units.
In the six months to November 30, operating revenue rose 2.8 per cent to $90.2m, while total income increased 3.6 per cent to $126.3m including changes to the fair value of its investment property. Net profit rose to $42.5m from $22m a year earlier.