ARGOMENTO:

Non so se a tutti sia chiara la differenza fra Initial e Maintenance Margin... vedo che qualcuno somma questo due valori (!)... altri che danno interpretazioni ancora più creative... vi riporto un articolato (in inglese) che mi sembra chiarisca bene la questione una volta per tutte


Participants in a futures contract are required to post performance bond margins in order to open and maintain a futures position.
Futures margin requirements are set by the exchanges and are typically only 2 to 10 percent of the full value of the futures contract.
Margins are financial guarantees required of both buyers and sellers of futures contracts to ensure that they fulfill their futures contract obligations.
Initial Margin

Before a futures position can be opened, there must be enough available balance in the futures trader's margin account to meet the initial margin requirement. Upon opening the futures position, an amount equal to the initial margin requirement will be deducted from the trader's margin account and transferred to the exchange's clearing firm. This money is held by the exchange clearinghouse as long as the futures position remains open.
Maintenance Margin

The maintenance margin is the minimum amount a futures trader is required to maintain in his margin account in order to hold a futures position. The maintenance margin level is usually slightly below the initial margin.
If the balance in the futures trader's margin account falls below the maintenance margin level, he or she will receive a margin call to top up his margin account so as to meet the initial margin requirement.

Example

Let's assume we have a speculator who has $10000 in his trading account. He decides to buy August Crude Oil at $40 per barrel. Each Crude Oil futures contract represents 1000 barrels and requires an initial margin of $9000 and has a maintenance margin level set at $6500.
Since his account is $10000, which is more than the initial margin requirement, he can therefore open up one August Crude Oil futures position.
One day later, the price of August Crude Oil drops to $38 a barrel. Our speculator has suffered an open position loss of $2000 ($2 x 1000 barrels) and thus his account balance drops to $8000.
Although his balance is now lower than the initial margin requirement, he did not get the margin call as it is still above the maintenance level of $6500.
Unfortunately, on the very next day, the price of August Crude Oil crashed further to $35, leading to an additional $3000 loss on his open Crude Oil position. With only $5000 left in his trading account, which is below the maintenance level of $6500, he received a call from his broker asking him to top up his trading account back to the initial level of $9000 in order to maintain his open Crude Oil position.
This means that if the speculator wishes to stay in the position, he will need to deposit an additional $4000 into his trading account.
Otherwise, if he decides to quit the position, the remaining $5000 in his account will be available to use for trading once again.

Per chi lavora con IB, attenzione comunque che il valore da mantenere controllato è lo Special Memorandum Account (SMA): se è prossimo a zero si rischia la chiusura d'ufficio.

Purtroppo lo SMA è nettamente minore del contante disponibile che risulta dopo aver sottratto i valori trattati da Luca. E non ho capito come venga calcolato, viaggia in modo abbastanza cervellotico, quindi va controllato sempre.

io l'SMA ce l'ho decisamente più alto della liquidità,ben 5 volte di più,per cui non capisco il conteggio. Comunque io mi regolo col Cushion,quello si che a volte può avvicinarsi allo zero,in tal caso vai in margin call

Anche io mi regolo col cushion , cerco d nn andar mai sotto 0,10 ! So x certo k a 0,05 di cushion IB inizia a chiudere posizioni in portafoglio!

Lo scorso Aprile ho avuto una sorpresa con IB, ho scritto, mi hanno risposto, e ho pubblicato qui la loro risposta: il valore da controllare sarebbe lo SMA, deve sempre essere maggiore di zero.
Siccome questo SMA dipende anche da indicazioni della SEC e della FED estemporanee, consigliavano perfino di controllarlo in orari prossimi alla chiusura, che sembrerebbero quelli più critici.
Riporto di nuovo un estratto della loro risposta.

The figures to watch for a Maintenance Margin violation are the Equity with Loan Value, Maintenance Margin and
Current Excess Liquidity. Traders want to be sure that the Equity with Loan Value does not fall below the
Maintenance Margin requirement. Current Excess Liquidity is the difference between the Equity with Loan Value
and the Maintenance Margin, so another way of saying this would be to make sure that the account has positive
Current Excess Liquidity at all times.
The US Fed has an enforcement period for Reg T—the SMA (Special Memorandum Account) balance, and that
time is 15:50-17:20 EST. The SMA must be a positive number during this time, or liquidations will occur to
make it positive. It is a good idea for traders to start looking at this figure between 15:00-15:30 to ensure the
account is complying with margin rules, and if not allowing ample time for decisions. If SMA is negative at
15:50, liquidation(s) is likely to occur very shortly thereafter.