August was a boon for passive investing, with major gains in AUM by issuers across Europe and in the US, according to data from Ultumus, an ETF data provider

In the US, ETFs saw huge inflows, with plain vanilla ETFs proving a strong draw - the biggest winners were SPDR S&P 500 (SPY), Schwab US Broad Market (SCHB) and iShares Russell 2000 (IRU) taking in $8bn between them.

While almost all providers did well, some did better than others. State Street came out on top, growing its AUM by $5.3bn over the month. Its stand out performer was SPY, which raked in a massive $4.6bn. As of 31 August, total AUM for SPY stood at $243bn, keeping it the biggest ETF in the world by far.

While State Street ETFs came out on top in August, they also came out bottom. Its gains in plain vanilla funds were tempered by $2.9bn worth of outflows in sector ETFs. The Consumer Discretionary Select Sector SPDR Fund alone saw $1.1bn in outflows.

In Europe iShares kept its crown, boasting the biggest winners and losers.

iShares Core Dax ETF (DAXEX), which tracks the biggest German companies, saw the most inflows, with $510 million entering the fund in August. The flows bring DAXEX total AUM to $10 billion.

BlackRock also clocked in Europe's biggest loser in August. The iShares EuroStoxx 50 (STTX), which tracks the 50 European bluechips, saw $667 million go out the door, bringing its total AUM down to $10.58 billion. Despite the outflows, STTX remains one of the biggest ETFs in Europe.

Commenting on the flows, Owen Rees, head of data at Ultumus said: "there are no clear trends or patterns were noticeable in this month's losers which are a mixed bag across equity and fixed income markets."

AUM change ($US million)
SPDR S&P 500 +$4,600
Consumer Discretionary Select Sector SPDR -$1,100
iShares Core Dax ETF +$510
iShares EuroStoxx 50 -$667

NAV Changes

NAV was a different story, and all about gas - which is perhaps to be expected given the well-noticed downward swing in energy markets this year.

The world's top performing ETF by NAV was the Direxion 3x inverse natural gas bear (GASX), which gives three times the inverse performance of natural gas. GASX, gained 37.3% in August, making it a clear winner.

The worst performer was Direxion's sister product, the 3x natural gas bull (GASL). GASL, which gives three times the daily return on natural gas, declined by 37.3%.

Among non-leveraged ETFs, the best bet was the iPath Global Carbon ETN (GRN) which went up 35.2%. Whoever said ESG investing never works?

The worst performer was REX VolMAXX Short VIX Weekly Futures Strategy ETF (VMIN), an actively managed ETF that gives inverse exposure to short-term VIX futures. VMIN declined in value by 16%.

NAV (percentage change)
iPath Global Carbon ETN +35.2%
REX VolMAXX Short VIX Weekly Futures Strategy ETF -16%
Direxion Daily Natural Gas Related Bear 3x Shares +37.3%
Direxion Daily Natural Gas Related Bull 3x Shares -37.3%