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The DR shock takes the same form as in Equation (4). 7. Page 9. We define anomaly returns as the value-weighted returns of stocks ranked in the highest quintile of a given firm characteristic minus the value-weighted returns of stocks ranked in the lowest quintile.
Accounting anomalies result from unusual processes or procedures in the accounting system. Several accounting anomalies are a result of fraudulent transactions. The three common accounting anomaly fraud symptoms involve problems with source documents, faulty journal entries, and inaccuracies in ledgers.
Market anomalies are distortions in returns that contradict the efficient market hypothesis (EMH). Pricing anomalies are when something—for example, a stock—is priced differently than how a model predicts it will be priced. Common market anomalies include the small-cap effect and the January effect.
Portfolios of companies with high book-to-market (BTM) ratio (low Price-To-Book (PB) ratios, Value firms) outperform those with companies with low BTM ratio (high PB ratios, Growth firms). In literature, this is known as the Value Anomaly.
Consider the following function:
Widget f(Widget w) {
return w;
}
Supposing that Widget implements both copy and move constructors, according to the C++ standard, w has to be treated as a rvalue object in the return statement, in case the compiler would not consider copy elision a better alternative.
On the other hand, consider the version below:
Widget f(Widget&& w) {
return w;
}
As opposite to the first version, according to Item 25 of Effective Modern C++, the author seems to be implying that returning w would certainly invoke the copy constructor. In other words, he suggests to return std::move(w) instead, in order to make the compiler use the (possibly faster) move constructor.
Can you explain why the second version of f() taking a Widget&& as argument is not equivalent to the first version taking a Widget by value with respect to the constructor being called in the return statement, also considering that in the body of both the functions the expression w refers to an lvalue?
Complete example demonstrating the behavior:
#include <iostream>
struct Widget
{
Widget() { std::cout << "constructed" << std::endl; }
~Widget() { std::cout << "destructed" << std::endl; }
Widget(const Widget&) { std::cout << "copy-constructed" << std::endl; }
Widget(Widget&&) { std::cout << "move-constructed" << std::endl; }
};
Widget
f1(Widget w)
{
return w;
}
Widget
f2(Widget&& w)
{
return w;
}
int
main()
{
f1(Widget {});
std::cout << std::endl;
f2(Widget {});
}
Output:
constructed
move-constructed
destructed
destructed
constructed
copy-constructed
destructed
destructed
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