/// <summary>
/// Get the maximum position group order quantity to obtain a position with a given buying power
/// percentage. Will not take into account free buying power.
/// </summary>
/// <param name="parameters">An object containing the portfolio, the position group and the target
/// signed buying power percentage</param>
/// <returns>Returns the maximum allowed market order quantity and if zero, also the reason</returns>
public override GetMaximumLotsResult GetMaximumLotsForTargetBuyingPower(
GetMaximumLotsForTargetBuyingPowerParameters parameters
)
{
if (parameters.PositionGroup.Count != 1)
{
return(parameters.Error(
$"{nameof(SecurityPositionGroupBuyingPowerModel)} only supports position groups containing exactly one position."
));
}
var position = parameters.PositionGroup.Single();
var security = parameters.Portfolio.Securities[position.Symbol];
var result = security.BuyingPowerModel.GetMaximumOrderQuantityForTargetBuyingPower(
parameters.Portfolio, security, parameters.TargetBuyingPower, parameters.MinimumOrderMarginPortfolioPercentage
);
var quantity = result.Quantity / security.SymbolProperties.LotSize;
return(new GetMaximumLotsResult(quantity, result.Reason, result.IsError));
}
/// <summary>
/// Get the maximum position group order quantity to obtain a position with a given buying power
/// percentage. Will not take into account free buying power.
/// </summary>
/// <param name="parameters">An object containing the portfolio, the position group and the target
/// signed buying power percentage</param>
/// <returns>Returns the maximum allowed market order quantity and if zero, also the reason</returns>
public virtual GetMaximumLotsResult GetMaximumLotsForTargetBuyingPower(
GetMaximumLotsForTargetBuyingPowerParameters parameters
)
{
// In order to determine maximum order quantity for a particular amount of buying power, we must resolve
// the group's 'unit' as this will be the quantity step size. If we don't step according to these units
// then we could be left with a different type of group with vastly different margin requirements, so we
// must keep the ratios between all of the position quantities the same. First we'll determine the target
// buying power, taking into account RequiredFreeBuyingPowerPercent to ensure a buffer. Then we'll evaluate
// the initial margin requirement using the provided position group position quantities. From this value,
// we can determine if we need to add more quantity or remove quantity by looking at the delta from the target
// to the computed initial margin requirement. We can also compute, assuming linearity, the change in initial
// margin requirements for each 'unit' of the position group added. The final value we need before starting to
// iterate to solve for quantity is the minimum quantities. This is the 'unit' of the position group, and any
// quantities less than the unit's quantity would yield an entirely different group w/ different margin calcs.
// Now that we've resolved our target, our group unit and the unit's initial margin requirement, we can iterate
// increasing/decreasing quantities in multiples of the unit's quantities until we're within a unit's amount of
// initial margin to the target buying power.
// NOTE: The first estimate MUST be greater than the target and iteration will successively decrease quantity estimates.
// 1. Determine current holdings of position group
// 2. If targeting zero, we can short circuit and return the negative of existing position quantities
// 3. Determine target buying power, taking into account RequiredFreeBuyingPowerPercent
// 4. Determine current used margin [we're using initial here to match BuyingPowerModel]
// 5. Determine if we need to buy or sell to reach the target and convert to absolutes
// 6. Resolve the group's 'unit' quantities, this is our step size
// 7. Compute the initial margin requirement for a single unit
// 7a. Compute and add order fees into the unit initial margin requirement
// 8. Verify the target is greater than 1 unit's initial margin, otherwise exit w/ zero
// 8a. Define minimum bounds on the target as target - (unit order margin + fees)
// 9. Assuming linearity, compute estimate of absolute order quantity to reach target
// 10. Begin iterating
// 11. For each quantity estimate, compute initial margin requirement
// 12. Compute order fees and add to the initial margin requirement
// 13. Check to see if current estimate yields is w/in one unit's margin of target (must be less than)
// 14. Compute a new quantity estimate
// 15. After 13 results in ending iteration, return result w/ direction from #5
var portfolio = parameters.Portfolio;
// 1. Determine current holdings of position group
var currentPositionGroup = portfolio.Positions[parameters.PositionGroup.Key];
// 2. If targeting zero, short circuit and return the negative of existing quantities
if (parameters.TargetBuyingPower == 0m)
{
return(parameters.Result(currentPositionGroup.Quantity));
}
// 3. Determine target buying power, taking into account RequiredFreeBuyingPowerPercent
var bufferFactor = 1 - RequiredFreeBuyingPowerPercent;
var targetBufferFactor = bufferFactor * parameters.TargetBuyingPower;
var totalPortfolioValue = portfolio.TotalPortfolioValue;
// 4. Determine initial margin requirement for current holdings
var currentSignedUsedMargin = 0m;
if (currentPositionGroup.Quantity != 0)
{
currentSignedUsedMargin = this.GetInitialMarginRequirement(portfolio, currentPositionGroup);
}
// 5. Determine if we need to buy or sell to reach target, we'll work in the land of absolutes after this
var signedTarget = targetBufferFactor * totalPortfolioValue - currentSignedUsedMargin;
var globalTarget = Math.Abs(signedTarget);
var direction = Math.Sign(signedTarget);
// 6. Resolve 'unit' -- this defines our step size
var groupUnit = parameters.PositionGroup.Key.CreateUnitGroup();
// 7. Compute initial margin requirement for a single unit
var absUnitMargin = this.GetInitialMarginRequirement(portfolio, groupUnit);
if (absUnitMargin == 0m)
{
// likely due to missing price data
var zeroPricedPosition = parameters.PositionGroup.FirstOrDefault(
p => portfolio.Securities.GetValueOrDefault(p.Symbol)?.Price == 0m
);
return(parameters.Error(zeroPricedPosition?.Symbol.GetZeroPriceMessage()
?? $"Computed zero initial margin requirement for {parameters.PositionGroup.GetUserFriendlyName()}."
));
}
// 7a. Compute fees for a single unit - if fees and price are linear, we'll be able to solve exactly w/out iteration
var contemplatedOrderFees = GetOrderFeeInAccountCurrency(portfolio, groupUnit);
absUnitMargin += contemplatedOrderFees;
// 8. Verify target is more that the unit margin -- for groups, minimum is same as unit margin
if (absUnitMargin > globalTarget)
{
return(parameters.SilenceNonErrorReasons
? parameters.Zero()
: parameters.Zero(
$"The target order margin {globalTarget} is less than the minimum initial margin: {absUnitMargin}"
));
}
// 9. Compute initial position group quantity estimate -- group quantities are whole numbers [number of lots/unit quantities]
var positionGroupQuantity = Math.Floor(globalTarget / absUnitMargin);
var positionGroup = groupUnit.WithQuantity(positionGroupQuantity);
// 9a. Compute fees for initial estimate and adjust targets. We take fees out of the target to decouple it from the quantity root finding
// 10. Begin iterating until order quantity is within target absFinalOrderMargin bounds (coming from above)
var loopCount = 0;
const int maxLoopCount = 5;
contemplatedOrderFees = GetOrderFeeInAccountCurrency(portfolio, positionGroup);
var orderMarginWithoutFees = this.GetInitialMarginRequirement(portfolio, positionGroup);
var orderMargin = orderMarginWithoutFees + contemplatedOrderFees;
// 8a. Define lower bounds on target, we seek an order that is >= targetMinimum and <= target
var target = Math.Abs(targetBufferFactor * (totalPortfolioValue - contemplatedOrderFees) - currentSignedUsedMargin);
var targetMinimum = target - absUnitMargin;
var lastOrderQuantity = 0m;
while (orderMarginWithoutFees > target || orderMarginWithoutFees < targetMinimum)
{
// Evaluate delta target and compute new quantity estimate
var deltaTarget = target - orderMarginWithoutFees;
var marginPerUnit = orderMarginWithoutFees / positionGroupQuantity;
var deltaQuantity = (int)Math.Floor(deltaTarget / marginPerUnit);
if (deltaQuantity == 0)
{
deltaQuantity = orderMarginWithoutFees > target ? -1 : 1;
}
positionGroupQuantity += deltaQuantity;
if (positionGroupQuantity <= 0)
{
return(parameters.Zero(
$"The target order margin {target} is less than the minimum {absUnitMargin}"
));
}
ArgumentException error;
if (UnableToConverge(lastOrderQuantity, positionGroupQuantity, groupUnit, portfolio, target, orderMargin, absUnitMargin, contemplatedOrderFees, out error))
{
throw error;
}
if (loopCount >= maxLoopCount)
{
break;
}
// 12. Update order margin with new quantity estimate
positionGroup = positionGroup.WithQuantity(positionGroupQuantity);
contemplatedOrderFees = GetOrderFeeInAccountCurrency(portfolio, positionGroup);
orderMarginWithoutFees = this.GetInitialMarginRequirement(portfolio, positionGroup);
orderMargin = orderMarginWithoutFees + contemplatedOrderFees;
loopCount++;
lastOrderQuantity = positionGroupQuantity;
// Update margin per unit so we can refine our targets
marginPerUnit = orderMarginWithoutFees / positionGroupQuantity;
// if we're iterating, it's possible that we have an exotic/non-linear fee or price structure
// to remove a potential source of non-linearity, we deduct the fees from our target to focus on quantity root finding
target = Math.Abs(targetBufferFactor * (totalPortfolioValue - contemplatedOrderFees) - currentSignedUsedMargin);
targetMinimum = target - marginPerUnit;
}
// 15. Incorporate direction back into the result
return(parameters.Result(direction * positionGroupQuantity));
}
