The initial margins can vary greatly and they don change as market conditions dictate. Below is a list of current futures margins for many of the popular commodity futures contracts. This is just an example and many commodity brokers have different margin rates. These are good example futures margin rates as of September 24, 2008.
10-Year T-Notes: $1,620
30-Year T-Bonds: $2,160
Cocoa: $2,940
Coffee: $4,200
Copper: $7,763
Corn: $2025
Cotton: $2,520
Crude oil: $12,488, mini contract: $6,244
Dollar Index: $1,330
Dow Index (Mini): $3,503
E-mini S&P: $4,500
Euro currency: $3,240
Gold: $7,428, mini contract: $2,476
Heating oil: $14,175, mini contract: $7,088
Lean Hogs: $1,215
Live cattle: $1,080
Nasdaq E-mini: $2,750
Natural gas: $12,825, mini contract: $3,206
Orange juice: $1,820
RBOB Unleaded gas: $13,500, mini contract: $6,750
Russell E-mini: $5,250
Silver: $8,100, mini contract: $1,620
Soybeans: $4,725
Sugar: $1,260
Wheat: $4,050

