Traded Funds are essentially Index Funds that are listed and traded on stock exchanges like other stocks. These investment vehicles allow investors to purchase a group of securities in a single transaction. 

The primary job of an ETF portfolio manager is to handle portfolio investments. The portfolio manager is ultimately responsible for making the decisions on investments that are to be included in the fund's portfolio. An ETF manager engages in ongoing research and equity or other asset evaluation, keeping track of market activity and trends, and monitoring economic news and conditions that may affect the portfolio's profitability. 

An ETF’s market price is the price at which investors can buy or sell an ETF on an exchange. This price may deviate from the NAV of the ETF depending on demand and supply for the ETF at a point in time. The price is usually expressed as a Bid price (the price a buyer is willing to pay for security) and an Offer price (the price that a seller is willing to accept for security).

NAV of ETF is most often expressed as the value per share. An ETF’s official NAV is calculated once a day, based on the most recent closing prices of the underlying securities.

The Shares of ETFs are freely traded on exchanges throughout the trading day, bought and sold by shareholders. An ETF portfolio manager is not burdened with handling actual transactions for shares.

So, the portfolio manager does not control the prices directly. The manager takes decisions regarding the stocks or investments that are to be included in the ETF. These changes made by the managers influence the cost of the unit of ETF.