"It's just saying that investors and wider stakeholders need to understand each company's approach to diversity, because the research is irrefutable. Diverse boards perform better."
Withers said she has never had a problem finding very skilled women across all areas and she has been against quota systems.
She said all the women she works with on boards are there because of their competence, and can hack it with any of the male directors.
"This is saying look, we need to be utilising as a nation the whole talent pool that we've got."
Withers hopes the NZX private companies will follow suit.
The new NZX code has eight parts, including a section on remuneration which recommends companies disclose the pay package in place for their chief executive in the annual report.
Currently companies only have to report the number of people who earn over $100,000 and how many people earn in salary bands above that.
The code will be enforced from October 1.