Yorkville ETF Advisors, a New York-based asset management firm, is in the process of gaining regulatory permission to offer index ETFs, the latest in a string of smaller firms that hope to join the rapidly expanding world of exchange-traded funds.

The firm said its first fund would be an equity fund focused on U.S. companies, and noted that future funds would focus on domestic or foreign securities, in both the fixed-income and equities realms. Yorkville also said it might roll out blended funds that focus on both equities and fixed income, according to the latest “exemptive relief” filing it made with the Securities and Exchange Commission.

Yorkville is the third small-sized firm to file to offer ETFs in a month. Late in June, Maine-based Forum Investment Advisors filed to offer actively managed ETFs, the first one focused on fixed income. Then, early in July, a Palo Alto, Calif.-based firm by the name of Wealthfront filed to gain permission to offer active ETFs focused on both equities and fixed income.

The ETF world continues to attract new players and new ideas 18 years after the first U.S.-listed was rolled out. Assets this year alone have grown almost 11 percent to more than $1.119 trillion, according to data compiled by IndexUniverse. That first fund, the SPDR S&P 500 ETF (NYSEArca: SPY) now has $94.35 billion in assets, and it’s only a matter of time before SPY crosses the $100 billion threshold.

Exemptive relief filings grant the ETF firms exception to sections of the Investment Act of 1940 and are just the first step in the path to launching ETFs. It often takes at least six to 12 months from the date of the initial filing for a company’s first ETF to hit the market, though active ETF filings can take longer.

Yorkville first filed for exemptive relief in February 2011.