Free is no longer cheap enough in the ultra-competitive market for exchange-traded funds.

Salt Financial, which currently runs one $10 million ETF, plans to woo buyers with a fund that will temporarily pay them to invest, according to regulatory filings. During the first year, holders will receive 50 cents for every $1,000 in a new low-volatility stock ETF -- until it grows to $100 million when the cash-back benefit will be capped and shared with all investors. The rebate is until at least April 2020, when a $2.90 management fee could kick in.

Asset managers are getting increasingly aggressive on price as they seek to stand out in an ETF marketplace with more than 2,000 options. Salt Financial plans to fast-track its growth by undercutting them all. If the move is successful and lures investments quickly, that could allow the company to overcome minimum-asset requirements enforced by some large broker-dealers that restrict which funds their advisers can buy.

“The distribution channel for newer products is inhospitable for new issuers,” Salt Financial’s Tony Barchetto wrote in a comment letter to the Federal Trade Commission in January. “The most common ‘gates’ that new funds face are based on assets under management, liquidity, or time since the fund launched.”

The company will spend as much as $50,000 (on top of costs associated with running the fund) to encourage investors to move over.

The cheapest ETFs currently charge just 30 cents for every $1,000 invested, data compiled by Bloomberg show. Vanguard Group, BlackRock Inc., State Street Corp. and Charles Schwab Corp. all offer broad stock funds at this price. Factor-based equity funds, like low volatility, charge an average $4.40.

Costs have been falling fast. Social Finance Inc., the online lender known as SoFi, won’t charge a management fee for at least a year on two funds its helping start, regulatory documents showed last month. JPMorgan Chase & Co. meanwhile unveiled plans for the cheapest ETF yet this week.