
make predictions biased toward one specific mode [14], [15].
Another approach is ensemble-based uncertainty estimation,
which focuses on the dispersion of predictions [15]–[17].
These methods are experimentally confirmed to be more robust
to dataset shift than methods that explicitly learn distribu-
tions [15], [17]. That is effective in predicting a dynamic
environment, such as financial markets.
Based on the above studies, we propose a novel approach
called the Uncertainty Aware Trader-Company (UTC) method.
The core idea of this approach is to combine the strengths of
both frameworks by merging the TC method with the proba-
bilistic modeling framework. We expect to retain the predictive
power and interpretability of the TC method while capturing
the uncertainty. To be more concrete, we propose the method
of estimating the prediction’s uncertainty from the Traders’
output. We estimate the variance by the two-stage algorithm:
estimation by the Trader and estimation by the Company.
The Trader estimates the uncertainty on weighting given a
trader’s strategy while the Company estimates the uncertainty
about the effectiveness of the whole traders’ strategies. We
theoretically show that our uncertainty estimation reflects the
posterior variance of predictive return given the past return.
Also, we prove that the predictive return of the UTC method
is identical to that of the original TC method under some
assumptions in the prior distribution of traders. That means
our method does not introduce additional biases.
We conduct a comprehensive evaluation of our approach
based on the synthetic and real market datasets. Our evaluation
of the synthetic datasets demonstrates that the UTC method
can detect situations where the uncertainty increases and the
prediction is difficult. We also confirmed that our method can
detect abrupt changes of data generating distributions. Further-
more, experiments using actual data show that the investment
strategy based on our UTC method gains stable returns while
suppressing risks compared to existing investment strategies.
The remainder of this paper is organized as follows. Section
2 describes our problem formulation and TC method briefly.
Section 3 presents our UTC method and theoretical properties.
Section 4 performs experiments. Section 5 reviews the related
work, and Section 6 is the conclusion.
II. PRELIMINARY
In this section, we formulate our problem and then provide
the overview of the TC method [9].
A. Problem Formulation
Our problem is to forecast future returns of stocks based on
their historical observations.
Let Xi[t]be the price of stock iat time twhere 1≤i≤S
denotes the index of stocks and 0≤t≤Tdenotes the time
index. We use the logarithmic returns of stock prices as input
features of models; we denote the one period ahead return of
stock iby
ri[t] := log(Xi[t]/Xi[t−1]) ≈Xi[t]−Xi[t−1]
Xi[t−1] .(1)
TABLE I
NOTATION.
Notation Meaning Def.
Xi[t]stock price of stock iat time t
where 1≤i≤S, 0≤t≤T§II-A
ri[t]logarithmic return of iat t(1)
ri[u:v] (ri[u],··· , ri[v]) (2)
ri:j[u:v] (ri[u:v],··· , rj[u:v]) (2)
ˆri[t+ 1],ˆσi[t+ 1] predicted value and standard deviation of ri[t](4)
M, Pj, Qj, Dj
Fj, Aj, Ojhyper-parameters of Traders (5)
Then we define the returns of stock iand returns of multiple
stocks 1≤i≤j≤Sfrom time period uto v(u≤v)by
ri[u:v] := (ri[u],· · · , ri[v]),(2)
ri:j[u:v] := (ri[u:v],· · · , rj[u:v]) (3)
We can formulate our main problem as follows.
Problem 1 (one-period-ahead prediction).We sequentially ob-
serve the returns ri[t](1≤i≤S) at every time 0≤t≤T−1.
We predict the one-period-ahead return ri[t+ 1] and estimate
its predictive uncertainty σi[t+ 1] based on the past treturns
r1:S[0 : t]. That is, the one-period-ahead return and uncertainty
prediction can be written as
ˆri[t+ 1],ˆσi[t+ 1] = ft(r1:S[0 : t]) (4)
for some function ft. The purpose of this study is to find ft
whose output ˆri[t+ 1] approximates the true return ri[t+ 1]
and predictive standard deviation ˆσi[t+ 1] approximates the
estimation error between ˆri[t+ 1] and ri[t+ 1] well.
B. Trader Company Method
This section introduces the Trader-Company method briefly.
The TC method consists of two main components, Traders and
Companies. A Trader predicts the returns using a simple model
expressing realistic trading strategies, while a Company com-
bines strategies from multiple Traders into a single prediction.
A Company applies an evolutionary algorithm that mimics
the role of financial institutes as employers of traders. During
training, a Company generates promising new candidates for
Traders and deletes poorly performing ones. We provide more
detailed definitions and training algorithms for the TC method.
1) Traders - Simple Prediction Module:
Definition 1. A Trader is a predictor of one period ahead
returns defined as follows. Let Mbe the number of terms
in the prediction formula. For each 1≤j≤M, we define
Pj, Qjas the indices of the stock to use, Dj, Fjas the delay
parameters, Ojas the binary operator, Ajas the activation
function, and wjas the weight of the j-th term. Then, the