diff --git a/ledger/predict.go b/ledger/predict.go
index 55d2238..9450c38 100644
--- a/ledger/predict.go
+++ b/ledger/predict.go
@@ -2,9 +2,10 @@ package ledger
 
 import (
 	"fmt"
-	"io"
 	"maps"
 	"regexp"
+	"slices"
+	"sort"
 	"time"
 )
 
@@ -12,26 +13,97 @@ func RegisterWithContributionPrediction(reg Register, window time.Duration) (Reg
 	result := make(Register)
 	result.PushAll(reg)
 	for _, name := range result.Names() {
-		subregister, err := registerWithContributionPredictionForName(result, window, name)
+		err := registerWithContributionPredictionForName(result, window, name)
 		if err != nil {
 			return nil, err
 		}
-		result.PushAll(subregister)
 	}
 	return result, nil
 }
 
-func registerWithContributionPredictionForName(reg Register, window time.Duration, name string) (Register, error) {
-	return nil, io.EOF
+func registerWithContributionPredictionForName(reg Register, window time.Duration, name string) error {
+	currencies := make(map[Currency]int)
+	for d := range reg {
+		for c := range reg[d][name] {
+			currencies[c] = 1
+		}
+	}
+	for c := range currencies {
+		err := registerWithContributionPredictionForNameForCurrency(reg, window, name, c)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
 }
 
-func registerWithContributionPredictionForNameForCurrency(reg Register, window time.Duration, name string, currency Currency) (Register, error) {
-	return nil, io.EOF
-	// find median contribution value+frequency in most recent half
-	// find median contribution value+frequency in most recent quarter
-	// find median contribution value+frequency in most recent eighth
-	// weighted averages of medians
-	// project
+func registerWithContributionPredictionForNameForCurrency(reg Register, window time.Duration, name string, currency Currency) error {
+	type contribution struct {
+		t time.Time
+		v float64
+	}
+	contributions := make([]contribution, 0)
+	for d := range reg {
+		t, err := dateToTime(d)
+		if err != nil {
+			return err
+		}
+		if v, ok := reg[d][name][currency]; ok {
+			contributions = append(contributions, contribution{t: t, v: v})
+		}
+	}
+	sort.Slice(contributions, func(i, j int) bool {
+		return contributions[i].t.Before(contributions[j].t)
+	})
+
+	getMedianValueDelta := func(contributions []contribution) float64 {
+		values := make([]float64, len(contributions))
+		for i := 1; i < len(contributions); i++ {
+			values[i] = contributions[i].v - contributions[i-1].v
+		}
+		slices.Sort(values)
+		return values[len(values)/2]
+	}
+	getMedianLapse := func(contributions []contribution) time.Duration {
+		lapses := make([]time.Duration, len(contributions)-1)
+		for i := 1; i < len(contributions); i++ {
+			lapses = append(lapses, contributions[i].t.Sub(contributions[i-1].t))
+		}
+		slices.Sort(lapses)
+		return lapses[len(lapses)/2]
+	}
+
+	eighth := contributions[int(7.0*len(contributions)/8.0):]
+	quarter := contributions[int(3.0*len(contributions)/4.0):]
+	half := contributions[int(1.0*len(contributions)/2.0):]
+	medianValueDelta := func() float64 {
+		return (4.0*getMedianValueDelta(eighth) + 2.0*getMedianValueDelta(quarter) + 1.0*getMedianValueDelta(half)) / (4.0 + 2.0 + 1.0)
+	}()
+	medianLapse := func() time.Duration {
+		return (4.0*getMedianLapse(eighth) + 2.0*getMedianLapse(quarter) + 1.0*getMedianLapse(half)) / (4.0 + 2.0 + 1.0)
+	}()
+
+	latest := func() float64 {
+		max := 0.0
+		for d := range reg {
+			if other := reg[d][name][currency]; other > max {
+				max = other
+			}
+		}
+		return max
+	}()
+	for _, predictionTime := range predictionTimes(window) {
+		k := predictionTime.Format("2006-01")
+		if _, ok := reg[k]; !ok {
+			reg[k] = make(Balances)
+		}
+		if _, ok := reg[k][name]; !ok {
+			reg[k][name] = make(Balance)
+		}
+		expectedDelta := float64(predictionTime.Sub(time.Now())) * medianValueDelta / float64(medianLapse)
+		reg[k][name][currency] = latest + expectedDelta
+	}
+	return nil
 }
 
 func BPIsWithFixedGrowthPrediction(bpis BPIs, window time.Duration, pattern string, apy float64) (BPIs, error) {
diff --git a/ledger/predict_test.go b/ledger/predict_test.go
index 1964393..5616cea 100644
--- a/ledger/predict_test.go
+++ b/ledger/predict_test.go
@@ -16,13 +16,15 @@ func TestRegisterPrediction(t *testing.T) {
 		}
 		t.Logf("%+v", got)
 
-		if len(got) != len(input)+1 {
+		if len(got) != len(input)+13 {
 			t.Error(len(got))
 		}
-		if _, ok := got["2001-11"]; !ok {
-			t.Error(ok)
+
+		for _, date := range got.Dates() {
+			for _, name := range got.Names() {
+				t.Logf("%s | %s = %+v", date, name, got[date][name])
+			}
 		}
-		t.Error("not impl")
 	})
 
 	t.Run("compounding interest", func(t *testing.T) {
diff --git a/ledger/register.go b/ledger/register.go
index 062c07b..85f0624 100644
--- a/ledger/register.go
+++ b/ledger/register.go
@@ -8,7 +8,12 @@ import (
 type Register map[string]Balances
 
 func (register Register) PushAll(other Register) {
-	TODO
+	for date := range other {
+		if _, ok := register[date]; !ok {
+			register[date] = make(Balances)
+		}
+		register[date].PushAll(other[date])
+	}
 }
 
 func (register Register) Names() []string {