After weeks of falling, broadly defined commodities rallied sharply last week (through April 3) and posted the biggest gain for the major asset classes, based on a set of exchange-traded funds. The first gain in six weeks for raw materials overall may be fleeting, but for the moment the rear-view mirror for this corner of markets is looking up.

The iShares S&P GSCI Commodity-Indexed Trust (GSG) surged 5.9% for the week through Friday’s close. The rally marked the fund’s first weekly gain since mid-February.

The key source of the price jump: reports that OPEC and Russia agreed to meet to hammer out a production cut in oil to aid the ailing market, which is oversupplied by a hefty degree. But over the weekend the meeting was reportedly delayed and oil prices are lower on Monday. As CNBC reports today:

Tensions between Saudi Arabia and Russia escalated on Friday, and the meeting will now “likely” be held on Thursday, according to sources familiar with the matter.

“It’s probably going to crater,” Again Capital’s John Kilduff said of oil. “There was a lot of optimism priced into oil Thursday and Friday. With this new Saudi, Russia spat, it doesn’t look like it’s going to come together.”

Meanwhile, inflation-indexed Treasuries posted the second-best rise for the major asset classes last week. The iShares TIPS Bond (TIP) gained 1.1%, marking the ETF’s third straight weekly advance.

Most of the major asset classes lost ground again last week. The biggest setback: US real estate investment trusts (REITs). Vanguard Real Estate (VNQ) tumbled 7.9%.

The Global Market Index (GMI.F) also fell in last week’s trading. This unmanaged benchmark that holds all the major asset classes (except cash) in market-value weights via ETFs shed 2.2%.

For the one-year trend, inflation-indexed Treasuries and investment-grade US bonds are neck-and-neck with gains. The iShares TIPS Bond (TIP) is up 10% on a total return basis vs. the year-ago price (based on trailing 252 trading days). In close second-place: Vanguard Total US Bond Market (BND), which is ahead by 9.6% on a total return basis for the one-year window through Friday’s close.

Commodities remain dead last: iShares S&P GSCI Commodity-Indexed Trust (GSG) has lost nearly 38% over the past 12 months.

GMI.F remains deep in the hole as well, suffering a 10.6% slide for the trailing one-year window as of Friday’s close.

For the moment, all the major asset classes are posting drawdowns, albeit in dramatically different degrees. Commodities (GSG) continue to post the deepest peak-to-trough decline: more than 70% below its previous price apex.

The smallest drawdown at last week’s close: iShares TIPS Bond (TIP), which was off a mere 0.8% from its previous high.