As smoke from one of Fletcher Building's major construction projects covered much of inner city Auckland, the company's share price rallied.
At around the same time, and mining and metals behemoth Rio Tinto was up to its old tricks again over Tiwai Point.
How could two of the week's big news stories possibly be related?
Rio Tinto's thinly veiled threat to shut down the NZAS smelter at Tiwai Point hit all the power generators hard - with Contact Energy faring the worst.
Talk in the market had been that Fletcher Building would drop out of an influential MSCI index and that Contact Energy would go in, with funds positioning themselves accordingly.
But with the future of Tiwai under a cloud, all bets were off.
Contact's share price tanked by 83c while Fletcher Building rallied by 6c, well before the fire at its Sky City convention centre project had been extinguished.
"The drop in Contact's share price, post NZAS, reduces the potential for Fletcher Building to come out of the MSCI benchmark," Harbour Asset Management portfolio manager Shane Solly said.
"Some traders and funds will have pre-positioned on the basis of Contact going in and Fletcher Building coming out," he said.
Fletcher, SkyCity shares recover after early fall, insurance questions clarified
NZ sharemarket blindsided by Rio Tinto's review of Tiwai Point
"It (Fletcher Building's rally) goes against grain of what you might have thought, given recent events," he said.
What is likely to go in and out of MSCI indices is never 100 per cent clear until it actually happens, but changes are expected be made known by the end of the month.
Rio Tinto, a Fortune 500 company which last year reported a net profit of US$13.6 billion, is no stranger to playing hardball when it comes to talking down the price of the key input for making aluminium - electricity.
We have been here before.
In 2013, Rio Tinto made similar noises just as Meridian Energy, Mercury Energy and Genesis were being prepared for partial privatisation by the Key government.
Now, those power generators have gone on to form the cornerstone of the market - even more so now that their share prices have been inflated by the yields that they can offer relative to low interest rates.
Was it just posturing from Rio Tinto? Maybe, but many in the market are not so sure.
The NZAS announcement had a big impact on the sharemarket.
Declines in the power generators - which make up 16 per cent of the sharemarket - helped drive the S&P/NZX50 index down by 2 per cent on the day.
Power generation has been at the forefront of the market's double-digit rally this year as investors piled into dividend yields stocks while interest rates continued their race to the bottom, but Matt Goodson, managing director at Salt Funds, doesn't think it's a big turning point for the market.
"The reaction looks overdone in isolation but it's from a start point where they had delivered extraordinary year-to-date performance in the chase for yield by investors who'd been forced out of bonds and term deposits and by anticipated upcoming MSCI index changes," he says.
"It's a timely reminder that equities are not term deposits," he said.
"Tiwai would seem to be cash generative at current aluminium prices and with sizeable rehabilitation costs, the most likely read is that they will continue producing at a lower power input price," he said.
"Then it becomes a question of how the pain is shared across the gentailer industry," he said.
Craigs Investment Partners head of institutional research, Grant Swanepoel, said when the Tiwai issue last arose in 2013, the smelter was assessed to be in the lower half of global efficiency. Now it is being flagged in the bottom quartile.
Swanepoel said the level of potential profitability is a concern "as it would appear the review is more than just about trying to leverage reduced electricity prices".
He put the chances of a Tiwai exit at 50 per cent.
As to the ramifications for what has been a very strong energy sector, Swanepoel said: "You probably don't have a bull dynamic supporting this sector while this overhangs it," he said.
"All you can say right now is that it does increase the risk that should be applied to the yield in this sector for a while," he said.
Ratings agency S&P Global said the electricity market's supply-demand balance would change fundamentally, affecting all of New Zealand's integrated electricity generators to varying degrees, if Tiwai closed.
"We anticipate that Genesis Energy and Contact Energy could face higher risk given their exposure to thermal generation," it said.
"Meridian Energy and Mercury are likely to face a lower degree of risk given their portfolios fully consist of renewable generating asset," S&P said.
The 12-month notice period for any movement in the energy offtake, however, should provide a reasonable lead-time for market participants to begin adapting to any change, S&P said.
Rally's end in sight?
Stephen Bennie at Castle Point funds said the the Tiwai renegotiation was effectively "ringing the bell" on the New Zealand equity bull market.
"The general share market problem is that, suddenly, we have an ever-growing camp of large New Zealand companies that are experiencing earnings headwinds.
That's a concern when the bulk of them are trading at prices that require solid, if not excellent, earnings growth.
"Typically, that gets resolved when either earnings start growing again or share prices go lower," Bennie said.
"And this is the 'perhaps' - either earnings growth returns or the New Zealand share market is going to find the going tougher from here."