diff --git a/src/main/java/edu/ntnu/idi/idatt/Exchange.java b/src/main/java/edu/ntnu/idi/idatt/Exchange.java
new file mode 100644
index 0000000..a159c4a
--- /dev/null
+++ b/src/main/java/edu/ntnu/idi/idatt/Exchange.java
@@ -0,0 +1,81 @@
+package edu.ntnu.idi.idatt;
+
+import edu.ntnu.idi.idatt.marked.Share;
+import edu.ntnu.idi.idatt.marked.Stock;
+import edu.ntnu.idi.idatt.transaction.Purchase;
+import edu.ntnu.idi.idatt.transaction.Sale;
+import edu.ntnu.idi.idatt.transaction.Transaction;
+
+import java.math.BigDecimal;
+import java.util.*;
+
+public class Exchange {
+
+    //TODO: JavaDocs, Write over functions mby
+
+    private final String name;
+    private int week;
+    private HashMap<String, Stock> stockMap = new HashMap<>();
+    private Random random = new Random();
+
+    public Exchange(String name, List<Stock> stocks) {
+        this.name = name;
+        this.week = 1;
+
+        for(Stock stock : stocks){
+            stockMap.put(stock.getSymbol(), stock);
+        }
+
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public int getWeek() {
+        return week;
+    }
+
+    public boolean hasStock(String symbol) {
+        return stockMap.containsKey(symbol);
+    }
+
+    public Stock getStock(String symbol) {
+        if(this.hasStock(symbol)){
+            stockMap.get(symbol);
+        }
+        return null; //TODO: Exception
+    }
+
+    public List<Stock> findStocks(String searchTerm) {
+        ArrayList<Stock> stocksFound = new ArrayList<>();
+
+        for(Stock stock : stockMap.values()) {
+            if(stock.getCompany().contains(searchTerm) || stock.getSymbol().contains(searchTerm)){
+                stocksFound.add(stock);
+            }
+        }
+        return stocksFound;
+    }
+
+    public Transaction buy(String symbol, BigDecimal quantity, Player player) {
+        Share share = new Share(getStock(symbol), quantity, BigDecimal.valueOf(random.nextDouble()));
+        Purchase purchase = new Purchase(share, this.week);
+        purchase.commit(player);
+        return player.getTransactionArchive().getPurchases(this.week).getLast();
+    }
+
+    public Transaction sell(Share share, Player player) {
+        Sale sale = new Sale(share, this.week);
+        sale.commit(player);
+        return player.getTransactionArchive().getSales(this.week).getLast();
+    }
+
+    public void advance() {
+        for(Stock stocks : stockMap.values()) {
+            stocks.addNewSalesPrice(BigDecimal.valueOf(random.nextDouble()));
+        }
+    }
+
+
+}
diff --git a/src/main/java/edu/ntnu/idi/idatt/Player.java b/src/main/java/edu/ntnu/idi/idatt/Player.java
new file mode 100644
index 0000000..cb2ae90
--- /dev/null
+++ b/src/main/java/edu/ntnu/idi/idatt/Player.java
@@ -0,0 +1,57 @@
+package edu.ntnu.idi.idatt;
+
+import edu.ntnu.idi.idatt.marked.Portfolio;
+import edu.ntnu.idi.idatt.transaction.TransactionArchive;
+
+import java.math.BigDecimal;
+
+public class Player {
+
+    private final String name;
+    private final BigDecimal startingMoney;
+    private BigDecimal money;
+    private Portfolio portfolio = new Portfolio();
+    private TransactionArchive transactionArchive = new TransactionArchive();
+
+    public Player(String name, BigDecimal startingMoney) {
+        this.name = name;
+        this.startingMoney = startingMoney;
+        this.money = this.startingMoney;
+    }
+
+    /**
+     * Getters
+     *
+     * @return - Their corresponding variables.
+     */
+
+    public String getName() {
+        return name;
+    }
+
+    public BigDecimal getMoney() {
+        return money;
+    }
+
+    public Portfolio getPortfolio() {
+        return portfolio;
+    }
+
+    public TransactionArchive getTransactionArchive() {
+        return transactionArchive;
+    }
+
+    /**
+     * Setters for money
+     *
+     * @param amount - Amount to be changed correspondingly.
+     */
+
+    public void addMoney(BigDecimal amount){
+        this.money = this.money.add(amount);
+    }
+
+    public void withdrawMoney(BigDecimal amount){
+        this.money = this.money.subtract(amount);
+    }
+}
diff --git a/src/main/java/edu/ntnu/idi/idatt/calculator/PurchaseCalculator.java b/src/main/java/edu/ntnu/idi/idatt/calculator/PurchaseCalculator.java
new file mode 100644
index 0000000..1bd3ae6
--- /dev/null
+++ b/src/main/java/edu/ntnu/idi/idatt/calculator/PurchaseCalculator.java
@@ -0,0 +1,70 @@
+package edu.ntnu.idi.idatt.calculator;
+
+import edu.ntnu.idi.idatt.marked.Share;
+
+import java.math.BigDecimal;
+
+/**
+ * PurchaseCalculator class
+ *
+ * <p>Calculates transaction price based on
+ * share bought.</p>
+ *
+ */
+public class PurchaseCalculator implements TransactionCalculator{
+
+    private final BigDecimal purchasePrice;
+    private final BigDecimal quantity;
+
+    /**
+     * Constructor for PurchaseCalculator
+     *
+     * @param share - The bought share
+     */
+    public PurchaseCalculator(Share share){
+        this.purchasePrice = share.getPurchasePrice();
+        this.quantity = share.getQuantity();
+    }
+
+    /**
+     * Method that calculates gross value
+     *
+     * @return - BigDecimal of purchase price x share quantity
+     */
+    @Override
+    public BigDecimal calculateGross() {
+        return purchasePrice.multiply(quantity);
+    }
+
+    /**
+     * Method that calculates the commission fee
+     *
+     * @return - BigDecimal of gross value x 0.5%.
+     */
+    @Override
+    public BigDecimal calculateCommision() {
+        BigDecimal fee = BigDecimal.valueOf(0.005); // Corresponding to 0.5%
+        return calculateGross().multiply(fee);
+    }
+
+    /**
+     * Method that calculates the tax
+     *
+     * @return - BigDecimal of 0 based on project requirements.
+     */
+    @Override
+    public BigDecimal calculateTax() {
+        return BigDecimal.ZERO;
+    }
+
+    /**
+     * Method that calculates the total price of a bought share
+     *
+     * @return - BigDecimal of gross value + commision fee + tax
+     */
+    @Override
+    public BigDecimal calculateTotal() {
+        return calculateGross().add(calculateCommision()).add(calculateTax());
+    }
+
+}
diff --git a/src/main/java/edu/ntnu/idi/idatt/calculator/SaleCalculator.java b/src/main/java/edu/ntnu/idi/idatt/calculator/SaleCalculator.java
new file mode 100644
index 0000000..3f59521
--- /dev/null
+++ b/src/main/java/edu/ntnu/idi/idatt/calculator/SaleCalculator.java
@@ -0,0 +1,76 @@
+package edu.ntnu.idi.idatt.calculator;
+
+import edu.ntnu.idi.idatt.marked.Share;
+
+import java.math.BigDecimal;
+
+
+/**
+ * SaleCalculator class
+ *
+ * <p>Calculates transaction profit based on
+ * share sold.</p>
+ *
+ */
+public class SaleCalculator implements TransactionCalculator{
+
+    private final BigDecimal purchasePrice;
+    private final BigDecimal salesPrice;
+    private final BigDecimal quantity;
+
+    /**
+     * Constructor for SaleCaculator
+     *
+     * @param share - The sold share
+     */
+    public SaleCalculator(Share share){
+        this.purchasePrice = share.getPurchasePrice();
+        this.salesPrice = BigDecimal.ZERO;  //TODO: Implement here
+        this.quantity = share.getQuantity();
+    }
+
+    /**
+     * Method that calculates gross value
+     *
+     * @return - BigDecimal of sale price x share quantity
+     */
+    @Override
+    public BigDecimal calculateGross() {
+        return salesPrice.multiply(quantity);
+    }
+
+    /**
+     * Method that calculates the commission fee
+     *
+     * @return - BigDecimal of gross value x 1%.
+     */
+    @Override
+    public BigDecimal calculateCommision() {
+        BigDecimal fee = BigDecimal.valueOf(0.01); // Corresponding to 1%
+        return calculateGross().multiply(fee);
+    }
+
+    /**
+     * Method that calculates the tax
+     *
+     * @return - BigDecimal of 30% of profit (gross - purchase price x quantity)
+     */
+    @Override
+    public BigDecimal calculateTax() {
+        BigDecimal taxPercentage = BigDecimal.valueOf(0.3); // Corresponding to 30%
+        BigDecimal profit = calculateGross().subtract(purchasePrice.multiply(quantity)); // gross - purchase price x quanitity
+        return profit.multiply(taxPercentage);
+
+    }
+
+    /**
+     * Method that calculates the total profit of a sold share
+     *
+     * @return - BigDecimal of gross value - commision fee - tax
+     */
+    @Override
+    public BigDecimal calculateTotal() {
+        return calculateGross().subtract(calculateCommision()).subtract(calculateTax());
+    }
+
+}
diff --git a/src/main/java/edu/ntnu/idi/idatt/calculator/TransactionCalculator.java b/src/main/java/edu/ntnu/idi/idatt/calculator/TransactionCalculator.java
new file mode 100644
index 0000000..a1f9265
--- /dev/null
+++ b/src/main/java/edu/ntnu/idi/idatt/calculator/TransactionCalculator.java
@@ -0,0 +1,21 @@
+package edu.ntnu.idi.idatt.calculator;
+
+import java.math.BigDecimal;
+
+/**
+ * TransactionCalculator interface
+ *
+ * <p>Contains methods that are used upon doing a transaction
+ * corresponding to a share and a week.</p>
+ * @see PurchaseCalculator
+ * @see SaleCalculator
+ *
+ */
+public interface TransactionCalculator {
+
+    BigDecimal calculateGross();                    // Gross        - Norsk: verdi før avgifter
+    BigDecimal calculateCommision();                // Commision    - Norsk: (Kurtasje) En avgift som betales til megleren.
+    BigDecimal calculateTax();                      // Tax          - Norsk: Skatt, en avgift som betales til staten.
+    BigDecimal calculateTotal();                    //                Totalverdi etter avgifter
+
+}
diff --git a/src/main/java/edu/ntnu/idi/idatt/marked/Portfolio.java b/src/main/java/edu/ntnu/idi/idatt/marked/Portfolio.java
new file mode 100644
index 0000000..535259b
--- /dev/null
+++ b/src/main/java/edu/ntnu/idi/idatt/marked/Portfolio.java
@@ -0,0 +1,65 @@
+package edu.ntnu.idi.idatt.marked;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Portfolio class
+ *
+ * <p>Class that functions as a wallet for a player
+ * storing all results of transactions made.</p>
+ *
+ */
+public class Portfolio {
+
+    private ArrayList<Share> shares;
+
+    /**
+     * Setter for ArrayList shares.
+     *
+     * @param share - The bought share
+     * @return - was the list modified?
+     */
+    public boolean addShare(Share share){
+        return shares.add(share);
+    }
+
+    /**
+     * Setter for ArrayList shares.
+     *
+     * @param share - The sold share
+     * @return - was the list modified?
+     */
+    public boolean removeShare(Share share){
+        return shares.add(share);
+    }
+
+    /**
+     * Getter for ArrayList shares.
+     *
+     * @return - List of all shares owned.
+     */
+    public List<Share> getShares() {
+        return shares;
+    }
+
+    /**
+     * Getter for ArrayList shares.
+     *
+     * @param symbol - The symbol of the stock corresponding to the share.
+     * @return - List of shares owned that corresponds with a company symbol.
+     */
+    public List<Share> getShares(String symbol) {
+        return shares.stream().filter(s -> s.getStock().getSymbol().equals(symbol)).toList();
+    }
+
+    /**
+     * Method for checking if the portfolio contains a specific share
+     *
+     * @return - If the share was found.
+     */
+    public boolean contains(Share share) {
+        return shares.contains(share);
+    }
+
+}
diff --git a/src/main/java/edu/ntnu/idi/idatt/marked/Share.java b/src/main/java/edu/ntnu/idi/idatt/marked/Share.java
new file mode 100644
index 0000000..1f9c14b
--- /dev/null
+++ b/src/main/java/edu/ntnu/idi/idatt/marked/Share.java
@@ -0,0 +1,49 @@
+package edu.ntnu.idi.idatt.marked;
+
+import java.math.BigDecimal;
+
+/**
+ * Share class
+ *
+ * <p>Class that describes the ownership of a specific stock.</p>
+ *
+ */
+public class Share {
+
+    private final Stock stock;
+    private BigDecimal quantity;
+    private BigDecimal purchasePrice;
+
+    /**
+     * Constructor for a Share.
+     *
+     * @param stock - The stock this share corresponds to.
+     *              @see Stock
+     * @param quantity - The total of bought shares of the stock.
+     * @param purchasePrice - The current price when the stock was bought.
+     */
+    public Share(Stock stock, BigDecimal quantity, BigDecimal purchasePrice) {
+        this.stock = stock;
+        this.quantity = quantity;
+        this.purchasePrice = purchasePrice;
+    }
+
+    /**
+     * Getters
+     *
+     * @return - Their corresponding variables.
+     */
+
+    public Stock getStock() {
+        return stock;
+    }
+
+    public BigDecimal getQuantity() {
+        return quantity;
+    }
+
+    public BigDecimal getPurchasePrice() {
+        return purchasePrice;
+    }
+
+}
diff --git a/src/main/java/edu/ntnu/idi/idatt/marked/Stock.java b/src/main/java/edu/ntnu/idi/idatt/marked/Stock.java
new file mode 100644
index 0000000..11ca9f8
--- /dev/null
+++ b/src/main/java/edu/ntnu/idi/idatt/marked/Stock.java
@@ -0,0 +1,68 @@
+package edu.ntnu.idi.idatt.marked;
+
+
+import java.math.BigDecimal;
+import java.util.List;
+
+/**
+ * Stock class
+ *
+ * <p>Class that describes an object of a unique stock.</p>
+ *
+ */
+public class Stock {
+
+    private final String symbol;
+    private final String company;
+    private final List<BigDecimal> prices;
+
+    /**
+     * Constructor for a Stock.
+     *
+     * @param symbol - String that indicates the symbol of a stock, ex. "APPL" as a short form of company.
+     * @param company - String, company name, ex. "Apple Inc."
+     * @param prices - An array of BigInteger that indicates the price corresponding with time.
+     */
+    public Stock(String symbol, String company, List<BigDecimal> prices) {
+        this.symbol = symbol;
+        this.company = company;
+        this.prices = prices;
+    }
+
+    /**
+     * Getters
+     *
+     * @return - Their corresponding variables.
+     */
+
+    public String getSymbol() {
+        return symbol;
+    }
+
+    public String getCompany() {
+        return company;
+    }
+
+    public List<BigDecimal> getPrices() {
+        return prices;
+    }
+
+    /**
+     * Getter for sale price
+     *
+     * @return - BigDecimal with current (newest in array) stock price.
+     */
+    public BigDecimal getSalesPrice() {
+        return prices.getLast();
+    }
+
+    /**
+     * Method that adds new price to the price array.
+     *
+     * @param price - BigDecimal, new price.
+     */
+    public void addNewSalesPrice(BigDecimal price) {
+        prices.add(price);
+    }
+
+}
diff --git a/src/main/java/edu/ntnu/idi/idatt/transaction/Purchase.java b/src/main/java/edu/ntnu/idi/idatt/transaction/Purchase.java
new file mode 100644
index 0000000..157c193
--- /dev/null
+++ b/src/main/java/edu/ntnu/idi/idatt/transaction/Purchase.java
@@ -0,0 +1,32 @@
+package edu.ntnu.idi.idatt.transaction;
+
+import edu.ntnu.idi.idatt.Player;
+import edu.ntnu.idi.idatt.calculator.PurchaseCalculator;
+import edu.ntnu.idi.idatt.calculator.TransactionCalculator;
+import edu.ntnu.idi.idatt.marked.Share;
+
+public class Purchase extends Transaction{
+    /**
+     * Constructor for a Purchase
+     *
+     * @param share      - The purchased share.
+     * @param week       - The current week
+     */
+    public Purchase(Share share, int week) {
+        super(share, week, new PurchaseCalculator(share));
+    }
+
+    /**
+     * @see Transaction
+     * @param player - The player that does the transaction
+     */
+    @Override
+    public void commit(Player player) {
+        player.withdrawMoney(this.getCalculator().calculateTotal());
+        player.getPortfolio().addShare(this.getShare());
+        player.getTransactionArchive().add(this);
+
+        this.commited = true;
+    }
+
+}
diff --git a/src/main/java/edu/ntnu/idi/idatt/transaction/Sale.java b/src/main/java/edu/ntnu/idi/idatt/transaction/Sale.java
new file mode 100644
index 0000000..d3dfee2
--- /dev/null
+++ b/src/main/java/edu/ntnu/idi/idatt/transaction/Sale.java
@@ -0,0 +1,31 @@
+package edu.ntnu.idi.idatt.transaction;
+
+import edu.ntnu.idi.idatt.Player;
+import edu.ntnu.idi.idatt.calculator.SaleCalculator;
+import edu.ntnu.idi.idatt.calculator.TransactionCalculator;
+import edu.ntnu.idi.idatt.marked.Share;
+
+public class Sale extends Transaction{
+    /**
+     * Constructor for a Sale
+     *
+     * @param share      - The sold share
+     * @param week       - The current week
+     */
+    public Sale(Share share, int week) {
+        super(share, week, new SaleCalculator(share));
+    }
+
+    /**
+     * @see Transaction
+     * @param player - The player that does the transaction
+     */
+    @Override
+    public void commit(Player player) {
+        player.addMoney(this.getCalculator().calculateTotal());
+        player.getPortfolio().removeShare(this.getShare());
+        player.getTransactionArchive().add(this);
+
+        this.commited = true;
+    }
+}
diff --git a/src/main/java/edu/ntnu/idi/idatt/transaction/Transaction.java b/src/main/java/edu/ntnu/idi/idatt/transaction/Transaction.java
new file mode 100644
index 0000000..1e955fe
--- /dev/null
+++ b/src/main/java/edu/ntnu/idi/idatt/transaction/Transaction.java
@@ -0,0 +1,66 @@
+package edu.ntnu.idi.idatt.transaction;
+
+import edu.ntnu.idi.idatt.Player;
+import edu.ntnu.idi.idatt.calculator.TransactionCalculator;
+import edu.ntnu.idi.idatt.marked.Share;
+
+/**
+ * Transaction class
+ *
+ * <p>An abstract class that handles a transaction
+ * based on week and share. Utilizes the calculators
+ * to perform calculations.</p>
+ * @see TransactionCalculator
+ */
+
+public abstract class Transaction {
+
+    private final Share share;
+    private int week;
+    private TransactionCalculator calculator;
+    protected boolean commited;
+
+    /**
+     * Constructor for a Transaction
+     *
+     * @param share - The share the transaction is about.
+     * @param week - The current week
+     * @param calculator - Transaction (Purchasae/Sale)
+     */
+    Transaction(Share share, int week, TransactionCalculator calculator) {
+        this.share = share;
+        this.week = week;
+        this.calculator = calculator;
+    }
+
+    /**
+     *
+     * Getters
+     * @return - their corresponding variable
+     *
+     */
+
+    public Share getShare() {
+        return share;
+    }
+
+    public int getWeek() {
+        return week;
+    }
+
+    public TransactionCalculator getCalculator() {
+        return calculator;
+    }
+
+    public boolean isCommited() {
+        return commited;
+    }
+
+    /**
+     * Abstract commit method to set the isCommited flag that symbolizes a unique transaction.
+     *
+     * @param player - The player that does the transaction
+     */
+    abstract public void commit(Player player);
+
+}
diff --git a/src/main/java/edu/ntnu/idi/idatt/transaction/TransactionArchive.java b/src/main/java/edu/ntnu/idi/idatt/transaction/TransactionArchive.java
new file mode 100644
index 0000000..3fbeaa4
--- /dev/null
+++ b/src/main/java/edu/ntnu/idi/idatt/transaction/TransactionArchive.java
@@ -0,0 +1,78 @@
+package edu.ntnu.idi.idatt.transaction;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * TransactionArchive class
+ *
+ * <p>Manages and handles transaction logic </p>
+ *
+ */
+public class TransactionArchive {
+
+    private final ArrayList<Transaction> transactions = new ArrayList<>();
+
+    /**
+     * Method for adding a new transaction to ArrayList transactions.
+     *
+     * @param transaction - The transaction instance
+     * @return - was the list modified?
+     */
+    public boolean add(Transaction transaction){
+        return transactions.add(transaction);
+    }
+
+    /**
+     * Method for checking if there has been any transactions previously.
+     *
+     * @return - was the transactions ArrayList empty?
+     */
+    public boolean isEmpty(){
+        return transactions.isEmpty();
+    }
+
+    /**
+     * Getter for transactions done
+     *
+     * @param week - Transaction interval
+     * @return - List of Transaction done in a specified week.
+     */
+    public List<Transaction> getTransactions(int week) {
+        return transactions.stream().filter(transaction -> transaction.getWeek() == week).toList();
+    }
+
+    /**
+     * Getter for purchases done
+     *
+     * @param week - Purchase interval
+     * @return - List of Purchase done in a specified week.
+     */
+    public List<Purchase> getPurchases(int week) {
+        return transactions.stream().filter(t -> t instanceof Purchase)
+                .map(t -> (Purchase) t)
+                .toList();
+    }
+
+    /**
+     * Getter for sales done
+     *
+     * @param week - Sale interval
+     * @return - List of Sale done in a specified week.
+     */
+    public List<Sale> getSales(int week) {
+        return transactions.stream().filter(t -> t instanceof Sale)
+                .map(t -> (Sale) t)
+                .toList();
+    }
+
+    /**
+     * Part 2
+     *
+     * @return
+     */
+    public int countDistinctWeeks(){ //TODO: HERE
+        return -1;
+    }
+
+}