The Deloitte South Island Index of listed companies shows overall market capitalisation of the 30 businesses up 17% on a year ago, across all seven sectors.
The fourth quarter 2015 results resulted in a marked turnaround of the previous three quarters, gaining a "phenomenal'' $2.04billion in market capitalisation, Scott McClay, a corporate finance partner in Deloitte's Christchurch, said.
The total market capitalisation, or dollar value of all shares combined, stood at $16.55billion in December.
"The result is the largest quarterly gain ever achieved by the index since its 2007 inception, with growth across all sectors,'' he said.
"In a rare occurrence, all seven industry sectors tracked by the index achieved positive results over the quarter,'' Mr McClay said.
The results ranged from 15.9% growth for the property sector down to 8.5% for the biotechnology sector.
There were 21 companies gaining, two unchanged and seven declining in market capitalisation.
The South Island listed companies collectively increased their market capitalisation by $2.04billion, up 14.1%, in the quarter ended December, and finished the calendar year 17.7% higher than the end of 2014.
"After the ups and downs of the first three quarters of 2015 it was heartening to see the strong performance of the index in the final quarter of the year,'' he said.
The property sector's result was led by Ryman Healthcare, announcing during the quarter it was on target for a 15% underlying profit growth for the year, while runner up the "other'' sector's performance was boosted by strong results from Moa Group, up 83.8%, Heartland Bank, up 18.8% and Skyline Enterprises, up 17.7%.
A large proportion of the considerable index growth during the quarter was attributed to three large companies collectively increasing $1.54billion in capitalisation, or by 14.1%.
Meridian Energy's market capitalisation was up $743.3million or 13.8%, Ryman Healthcare was up $595million or 16.3% and Ebos Group was up $203million or 10.8%.
"This phenomenal quarterly performance raises hope that the tide is turning back to positive performance. However, seasoned investors will be wary of the potential for this result being just a king tide,'' Mr McClay said in a statement.
He cautioned that the index's decline of 3.5% in January, after the fall in global markets following the New Year period, demonstrated South Island companies were not immune to global forces.
For the fourth quarter, the Deloitte index's 14.1% quarterly gain outpaced all international benchmark indices.
The S&P/NZX 50 Capital Index was up 12.5%, the Dow Jones gained 7% and the ASX All Ords was up 5.7% during the same period.
Even setting aside Meridian, Ryman and Ebos, Mr McClay said the remaining 27 companies achieved a strong result, collectively growing by $502million, or 14%, and the smallest 20 companies grew by a "solid'' $76.6million, or 6.9%.
The biggest declines in the dollar value of market capitalisation for the quarter were Silver Fern Farms, down $25.1million or 16.7%, South Port New Zealand at Bluff, down $8.4million or 6.7% and Foley Family wines, down $2.6million or 3.3%.
