Discount broker and ETF sponsor Charles Schwab (NYSEL SCHW) said today 16 ETFs will be added to its commission-free ETF platform, Schwab ETF OneSource.

California-based Schwab rolled out OneSource in February, giving its clients the opportunity to buy and sell 105 ETFs with zero online trade commissions. [Schwab Unveils Game-Changing ETF Platform]

The 16 new ETFs include five from Guggenheim, five from SPDR ETFs and six from Charles Schwab Investment Management. The newest additions to Schwab ETF OneSource expand the range of asset categories available to now include asset allocation, long-term corporate bond, and international asset-income ETFs, according to a statement issued by Schwab.

OneSource now offers 121 ETFs on a commission-free basis. In addition to funds from the aforementioned issuers, Schwab ETF OneSource features ETFs from PowerShares, the fourth-largest U.S. ETF sponsor, ETF Securities and U.S. Commodity Funds.

“With the most commission-free ETFs and the broadest category coverage in the industry, Schwab ETF OneSource gives investors and advisors unsurpassed choice when it comes to building diversified commission-free ETF portfolios,” said Beth Flynn, vice president of ETF platform management at Charles Schwab, in the statement. “We’re pleased to be adding to the range of funds and asset categories that we can offer commission-free, and continue to believe that this is just the beginning.”

Among the 16 ETFs added to Schwab ETF OneSource are Schwab’s six new fundamentally-weighted ETFs that track the Russell Fundamental Index Series, which is based on methodology developed by Rob Arnott and Research Affiliates. [Schwab to Launch Smart Beta ETFs]

Those funds include the Schwab Fundamental U.S. Broad Market Index ETF (NYSEArca: FNDB) and the Schwab Fundamental U.S. Large Company Index ETF (NYSEArca: FNDX).

Data indicate investors do appreciate low or, even better, no costs when it comes to trading ETFs.

“According to the 2013 ETF Investor Study by Charles Schwab, released earlier this month, the ability to trade ETFs commission-free is most or very important to 45 percent of investors. Notably, the study also highlighted the importance of another key fact about Schwab ETF OneSource – investors are not charged any early redemption fees or surprised with other costs for selling an ETF shortly after buying it. According to the study, clarity about a fund’s redemption fees or other hidden fees is considered the number one cost factor when making ETF buying decisions, with 71 percent saying it is extremely important,” Schwab said in the statement.

Schwab had $179 billion in ETFs custodied on its platform as of September 30, 2013. Schwab ETFs, including the new Schwab Fundamental Index ETFs, had $14.2 billion in assets as of September 30, 2013.

Full list of new OneSource ETF Addition