Only four of the seven sectors rose, of which energy and mining was the clear winner, driven by heavyweight Meridian Energy.
Conversely, the retail sector lost $200.4 million in value as a result of a poor performance by High St sport and leisure retailer Kathmandu.
Deloitte's corporate finance partner, Scott McClay, said the return of the index to positive territory, having booked two consecutive quarters of downturns, reflected the confidence of investors in the market.
South Island listed firms increased their market capitalisation (share price gains/losses) by $691.2 million, up 6.2%, for the quarter. The index ended the year at its highest recorded point since its inception in 2007, Mr McClay said.
''During the September 2014 quarter we saw the smaller companies stepping up and providing strength to the Deloitte South Island Index as the largest companies suffered from profit-taking and global trends following a remarkable period of growth,'' he said.
For the latest quarter the four largest companies on the index collectively grew 12.4%, he said.
The largest gain for the quarter, in dollar terms, was by Meridian, up $414.3 million, or 23%, driving almost all of the post-election movement in the energy and mining sector.
''Meridian was also benefiting from increased demand for electricity in the market, coupled with higher generation prices being achieved,'' Mr McClay said.
On an annual basis, following Meridian gaining $903.4 million, or 69%, Ryman Healthcare gained $335 million, or 8.5%, while Heartland New Zealand gained $194 million, or 58.1%.
While the energy and mining gained the most of the sectors, up $414.3 million or 23.1%, the retail sector plummeted by $200 million, down 30%.
For the year to December, the Deloitte South Island Index increased by $814.3 million, up 7.4%. Mr McClay said the performance put the index in the middle of the pack compared to the yearly performance of benchmark indices in percentage terms.
The NZX Capital Index gained 12.6%, the Dow Jones gained 7.5% and the ASX All Ords only gained 0.7% during the year to December.
Chatham Rock Phosphate had the largest percentage growth in market capitalisation during the quarter, up 104.4%, in part due to raising $3.5 million to support financial losses as it awaits the outcome applications to begin seabed mining.
Following Lyttelton Port Company's recent delisting, the Deloitte index has dropped the port sector. South Port has
now been recategorised into ''other'', the seventh sector covered.
