Treasury Bills (Margin)

[Real Money]

Let's say I'm holding 100k in 6month t bills.

The margin required is like $1000.

Then let's say I buy 50k worth of SPY.

I owe the full margin rate on the stock holdings right?

(whatever the current margin rate is at IBKR).

 

[cruisecontrol]

Let's say I'm holding 100k in 6month t bills.

The margin required is like $1000.

Then let's say I buy 50k worth of SPY.

I owe the full margin rate on the stock holdings right?

(whatever the current margin rate is at IBKR).

Correct. Assuming you have no other cash in the account, your net cash position would be -50K, and you would pay margin interest on that.

The tbills do not offset this in any way and the margin requirement has nothing to do with how margin debit interest is calculated. All that matters for interest is the settled cash in the account.

 

[Q.E.D.]

Let's say I'm holding 100k in 6month t bills.

The margin required is like $1000.

Then let's say I buy 50k worth of SPY.

I owe the full margin rate on the stock holdings right?

(whatever the current margin rate is at IBKR).

Rules may have changed, & there was no reason to employ this approach for most of past decade, but if instead of buying/shorting SPY, you used SP futures, one use to be able to use Treasury securities for margin requirements.

One only needed cash to cover the OTE / PL loss on the futures positions.

Of course brokers are not promoting above, as much / most (?) income for brokers are collecting interest on the free account balances of customers.

 

[taowave]

Are you sure about that??
I thought if you post 100k in T-bills as collateral,your buying power is reduced by 10%,leaving you with 90k to trade...

Correct. Assuming you have no other cash in the account, your net cash position would be -50K, and you would pay margin interest on that.

The tbills do not offset this in any way and the margin requirement has nothing to do with how margin debit interest is calculated. All that matters for interest is the settled cash in the account.

 

[cruisecontrol]

Are you sure about that??
I thought if you post 100k in T-bills as collateral,your buying power is reduced by 10%,leaving you with 90k to trade...

OP question as I interpreted it was about margin interest ("I owe the full margin rate on the stock holdings right?")

Buying power and such is a totally separate issue. For treasury bonds, the margin requirement depends on duration - see https://www.interactivebrokers.com/en/trading/margin-bonds.php. For 6 mo tbills it is only 1% not 10%.