For shareholders, new power is on the way.

On Wednesday, the Securities and Exchange Commission voted 3-2 in favor of proxy access, which will give shareholders more control over the directors chosen for company boards. This decision, which was 30 years in the making, represents a massive overhaul for the decision-making process among the boards of publicly-traded companies.

Under the new rules, companies will be required to inform shareholders of all nominees on the standard ballots, and investors will have the ability to nominate their own candidates to a company s board through the firm s proxy materials without having to wage a separate proxy fight. To win the right to nominate candidates, investors must own at least 3% of the company s stock for at least 3 years.

The impact on shareholders could be twofold. On one hand, the rule will upset the power balance between shareholders and chief executives, giving the former more control, more say in how the company is run and more influence over the board of directors.

From a longer-term standpoint, it s incredibly important that investors feel they have sufficient control over what companies do to believe that they re operating in their best interests, says Bruce McCain, senior vice president and chief investment strategist at Key Private Bank. This change gives shareholders the sense of greater control over their own destiny, and from that standpoint I think it s almost inevitable to have a bit of a net positive as far as share prices over the long term.

Critics say the decision could have negative consequences for shareholders. The two Republican SEC commissioners, Kathleen Casey and Troy Paredes, who voted against proxy access, say the new rule could create too much meddling from investors and could hamper quarterly earnings.

Shareholders can sometimes be a bit shorter term in their focus as opposed to looking at the longer-term strategic view that often management at least may have a better sense of, says McCain. It s possible that this rule will sway a corporation s long-term strategies closer to investors shorter-term concerns, which might not be in the best interest for its position within a market, he adds.

Critics have also expressed concern over the requirements for proxy access, which some say benefits short-term shareholders. Someone who s been investing in a company for three years could have different goals and profit-making strategies than the investor of 10 or more years, they say.