"It's not obviously value additive at first glance - Synlait will really need to use the added capacity they're creating to produce further value-added products down the track," said Matt Goodson, managing director at Salt Funds Management.
"The whole dairy space is very whippy at present, very significant up and down moves in reaction to information."
The two milk stocks went through a spell of mirroring each others' trading patterns, but have decoupled lately.
"It was odd they were so coupled in the first place," Goodson said.
"Synlait is the contract manufacturer whereas A2 had far more leverage to their marketing success in China. It was more about sentiment to the overall sector."
Property stocks were a little weaker today, after US ten-year bond yields rose above the 2.4 per cent barrier and closed about 2.45 per cent on the passage of tax legislation through the US Congress, Goodson said.
"Significant tax cuts at a time when your economy is near full employment would normally be inflationary, that has got people thinking about next year and what's likely to happen," he said.
"A lot of the previews we're seeing from strategists suggest somewhat higher bond yields, and property and utility names tend to be the most affected by that. That's one thing that has carried over to a modest degree in our market."
Kiwi Property fell 1.1 per cent to $1.40, Goodman Property dropped 0.7 per cent to $1.375, Argosy Property was down 0.5 per cent to $1.085, and Precinct Property declined 0.4 per cent to $1.365.
NZX rose 0.9 per cent to $1.11. It will change the price structure of the local stock market in the second half of next year as part of a new strategy aimed at reinvigorating the domestic capital market.
Outside the benchmark index, Abano Healthcare Group dipped 0.5 per cent to $9.95. It posted a 2 per cent gain in first-half profit to a record, meeting guidance while announcing the exit from its remaining non-dental business with the $17m sale of Ascot Radiology.
Veritas Investments rose 9.1 per cent, or 0.5 of a cent, to 6 cents. It has agreed to sell its Mad Butcher franchisor business to chief executive Michael Morton for $8m, less than a quarter of what he sold it to the food and beverage investor in a reverse listing almost five years ago.