NEW YORK ( TheStreet) -- Shaky market action weighed on the exchange traded product industry over the past month.According to the flow data compiled by the National Stock Exchange, total ETF/ETN assets dipped by $90 billion in September, closing out the month at $972 billion. This is the first time assets have broken below the $1 trillion mark since breaching this level in January. September's assets mark a decline of over $160 billion since April's peak. Despite the overall decline in assets, the total universe of exchange traded products continued to expand. Over the past month, 34 new products were added, bringing the total number of ETFs and ETNs to 1,335. Thanks to weak market conditions, nearly every ETF fund sponsor watched their total assets decline over the past month. Leading the retreat were industry leaders including Blackrock ( BLK), State Street ( SST) and Vanguard. This trio of firms watched their assets dip by a combined $74 billion. Companies including Van Eck, PowerShares and Rydex watched their assets dip between $1 billion and $4 billion each. Pimco was one of the few companies to buck this trend in September. During the month, the bond giant watched its total ETF assets grow by $64 million. A notable decline in assets is not necessarily indicative of heavy outflows. For example, of the three firms with the steepest asset losses over the past month, only State Street suffered net outflows. During September, the firm watched as $4.5 billion head for the exits. Meanwhile, Blackrock and Vanguard welcomed over $3.5 billion each. The main culprits leading to State Street's heavy outflows were the SPDR S&P 500 ETF ( SPY), Energy Select Sector SPDR ( XLE), SPDR S&P MidCap 400 ETF ( MDY) and SPDR Barclays Capital 1-3 Month T-Bill ETF ( BIL). These products, which represent four of the five top outflows leaders, watched $3.9 billion, $1.0 billion, $820 million, and $530 million flee for the exits. On the opposite side of the spectrum, iShares MSCI EAFE Index Fund ( EFA) was the biggest inflow recipient. In September, $3 billion entered the fund. Vanguard Emerging Markets ETF ( VWO), meanwhile, saw net inflows totaling $1.7 billion. Given the weak market conditions, it wasn't surprising to see ETFs linked to bonds, defensive sectors, and safe haven asset classes as some of the most popular funds during September. Vanguard Barclays Short Term Bond ETF ( BSV), PowerShares DB U.S. Dollar Index Bullish Fund ( UUP), Utilities Select Sector SPDR ( XLU), and Vanguard Barclays Total Bond ETF ( BND) were among the top 10 inflow leaders.