She said the looming Meridian float could be causing Mighty River Power investors to sell as well.
"We've got competitors coming into the market with Meridian's IPO later in the year but our focus is on driving shareholder value and we're going to have a laser sharp focus on doing that for our shareholders.
Asked whether the listing price was set too high Withers said: "That's a matter you should ask the Crown what they had was a great deal of uncertainty on some of those things, yes they were out there, there was no certainty about Tiwai which has happened since the IPO and obviously there's been more narrative around the Labour-Greens policy. Yield stocks have been punished given that the 10-year bond is up probably 100 basis points in that time."
Mighty River said net profit was $114.8 million in the year ended June 30, up from $67.7 million a year earlier. In its prospectus in April it forecast a profit of $94.8 million.
Sales fell 9 per cent to $1.38 billion and the company's energy margin, which is sales excluding line and energy costs, shrank 6.3 per cent to $678.3 million.
The full year dividend of 12 cents for the year amount to $168 million, in line with forecast and up from the $119.8 million it paid the government as sole owner a year earlier.
Earnings before interest, tax, depreciation, amortisation, fair value adjustments and equity accounted earnings fell to $390 million from $461 million a year earlier, reflecting one-off costs related to its international geothermal business and costs associated with the IPO.
Total generation fell 9 per cent to 6,462GWh, which the company said was mainly due to lower hydro volumes, which were down 8 per cent "as result of weak inflows into the Waikato catchments which were only 80 per cent of average for the second half of the year."
Withers said the company "remains comfortable" with its prospectus forecasts for 2014, including about 20 per cent growth in EBITDAF and an increase in annual dividends to 13 cents, reflecting the contribution from its new Ngatamariki geothermal plant and the absence of one-off costs in the 2013 financial year.
Capital expenditure was likely to be lower than forecast in the prospectus.
The company plans to update its guidance at the annual shareholders' meeting on November 7.
Withers said the outlook for power prices was flat.
"What we're seen is there is a flattening of demand at the retail level and more widely - obviously it's a very competitive market.