Abstract: |
The liberalization of the natural gas market in the European Union has created
incentives for the development of hubs and gas-to-gas competition. With
increasing spot trading, there has been a progressive shift in pricing
mechanisms from the traditional oil-linked pricing towards hub-linked pricing.
In 2014, the share of gas traded that was indexed to hubs reached 61%, which
can be compared to 15% in 2005 and 36% in 2010 (IGU, 2015). In addition, as
energy companies respond to their exposure to the spot market, a greater use
of forward contracts is made. In this context, liquidity, which can be
described as the ability to match buyers and sellers at the lowest transaction
cost (O’Hara, 1995) is of particular interest for researchers, participants
and policy makers. Liquidity affects the cost of hedging and investment
decisions and is a barometer of market quality. The importance of liquidity is
reflected in a vast literature that focuses on different classes of financial
assets such as stocks and bonds (e.g. Chordia et al. 2000, 2005) or foreign
exchanges (e.g. Bessembinder, 1994; Danielsson and Payne, 2012). There are
reports that liquidity may impact other measures of market quality, as for
example, price volatility (e.g. Subrahmanyam, 1994) and trading activity (e.g.
Chordia et al., 2002). Nevertheless, when academic studies of energy markets
are considered, to date liquidity appears to have been neglected. In the
present study, what may drive liquidity in the European natural gas market is
considered. The National Balancing Point (NBP) forward market, which is the
largest in Europe, is used as a proxy for the European natural gas forward
market. The link between liquidity, trading activity and volatility is
examined within the period 2010-2014, which includes when the EU Regulation on
Market Integrity and Transparency (REMIT) came into effect. Therefore, the
question of whether changes in link between these measures of market quality
could reflect REMIT is also investigated. A unique dataset consisting of
tick-by-tick indicative quotes (best ask and best ask) and transaction prices
and volumes, obtained from the inter-deal broker Tullett Prebon
http://www.tpinformation.com) is used. The data correspond to approximately a
third of the NBP month-ahead forward market in the period studied. In order to
account for the discrete and irregular nature of the data, cleaning and
resampling procedures based on Brownlees and Gallo (2006) and
Barndorff-Nielsen et al. (2009) is adopted. The focus is on the trading time
interval 7:00-17:00, and observations outside this interval are discarded, as
well as entries with negative spreads. Simultaneous quotes and transaction
prices are aggregated using their respective medians, volumes and transaction
counts are aggregated by using their respective totals. Outliers are detected.
In all, approximately 2% of the observations are discarded. The data are then
resampled at regular time intervals of 60 minutes leading to a sample size of
12,870 observations. Furthermore, the expected effect of the yearly
seasonality of the demand for natural gas on the link between these measures
is also addressed, and, in the spirit of Chordia et al. (2005), adjustment
regressions are performed on the raw series. A vector autoregressive (VAR)
model is adopted to investigate the link between liquidity, volatility and
trading activity in the NBP month-ahead forward market. This approach has been
used by Chordia et al. (2005), to investigate the correlation between
liquidity, volatility, returns and order imbalance in the stock market, and
Danielsson & Payne (2012), to analyze the correlation between volume,
volatility and spread in the foreign exchange markets. Compared to previous
research, a time-varying approach is used in this study, so that any change in
the links between the market quality measures can be assessed. Parameters are
estimated over rolling windows of fixed size (252 days, m=2,268) through the
sample in order to evaluate their stability. Consistent with microstructure
theory on asymmetric information (Glosten & Milgrom, 1985, Kyle, 1985; Easley
& O'Hara, 1987), we find a positive correlation between trading activity and
volatility plus a negative correlation between volatility and subsequent
liquidity. The analysis suggests, however, these correlations are time-varying
and follow changes in the fundamental values of demand, supply and inventory.
Overall, the present study suggests increases in market transparency and
competition over time. These findings are reassuring for policy makers and
regulators. Nonetheless, no significant differences in correlations appear to
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