As of December 31,
2018
2019
Cash and cash equivalents
342,594
263,747
Short-term investments
25,000
4,500
Trade and other receivables
20,244
24,900
Dividends receivable and other amounts due from related parties
33,395
573
Derivative financial instruments
15,188
4,001

text: GasLog Ltd. and its Subsidiaries
Notes to the consolidated financial statements (Continued)
For the years ended December 31, 2017, 2018 and 2019
(All amounts expressed in thousands of U.S. Dollars, except share and per share data)
text: Credit risk
text: Credit risk is the risk that a counterparty will fail to discharge its obligations and cause a financial loss and arises from cash and cash equivalents, short-term investments, favorable derivative financial instruments and deposits with banks and financial institutions, as well as credit exposures to customers, including trade and other receivables, dividends receivable and other amounts due from related parties. The Group is exposed to credit risk in the event of non-performance by any of its counterparties. To limit this risk, the Group currently deals primarily with financial institutions and customers with high credit ratings.
text: For the year ended December 31, 2019, 70.0% of the Group’s revenue was earned from Shell (December 31, 2018 and December 31, 2017, 74.2% and 92.6%, respectively) and accounts receivable were not collateralized; however, management believes that the credit risk is partially offset by the creditworthiness of the Group’s counterparties. BG Group was acquired by Shell on February 15, 2016. This acquisition does not impact the contractual obligations under the existing charter party agreements. The Group did not experience significant credit losses on its accounts receivable portfolio during the three years ended December 31, 2019. The carrying amount of financial assets recorded in the consolidated financial statements represents the Group’s maximum exposure to credit risk. Management monitors exposure to credit risk, and they believe that there is no substantial credit risk arising from the Group’s counterparties.
text: The credit risk on liquid funds and derivative financial instruments is limited because the counterparties are banks with high credit ratings assigned by international credit-rating agencies.

Questions:
question: How does the Group limit its exposure to credit risk?
answer: To limit this risk, the Group currently deals primarily with financial institutions and customers with high credit ratings.
question: When did Shell acquire BG Group?
answer: February 15, 2016
question: What are the components subjected to credit risk?
answer: Cash and cash equivalents
Short-term investments
Trade and other receivables
Dividends receivable and other amounts due from related parties
Derivative financial instruments
question: Which year was the cash and cash equivalents higher?
answer: 2018
derivation: 342,594 > 263,747
question: What was the change in short-term investments from 2018 to 2019?
answer: -20500
derivation: 4,500 - 25,000 
scale: thousand
question: What was the percentage change in derivative financial instruments from 2018 to 2019?
answer: -73.66
derivation: (4,001 - 15,188)/15,188 
scale: percent